Refine Markdown in README.md. [skip appveyor]

Move "by TTG" to the main header. Switch from the alternative headings
format, which allows for H1 and H2 only, to the main one, which allows
for H1 through H6. Have two H3 headers in the text. Fix CI badges to
point to libpcap instead of tcpdump, and to use .com URLs for Travis CI.
Make the security note bold to help more people actually get it. Add and
improve hyperlink formatting in a few places. Fence the "from LBL"
boilerplate and move it to the bottom of the first section. Make the
"NOT", which was bold in commit 4a0b801, but didn't survive the initial
Markdownization attempt in commit 82001f3, bold again. Escape filenames
and sonames properly.

Skip only some CI on this occasion, so Travis CI can transfer the build
history from travis-ci.org to travus-ci.com and complete the migration.

1 files changed, 26 insertions, 38 deletions

diff --git a/README.md b/README.md
index 1e3a245b..64eba61a 100644
--- a/README.md
+++ b/README.md
@@ -1,26 +1,16 @@
-LIBPCAP 1.x.y
-=============
+# LIBPCAP 1.x.y by [The Tcpdump Group](https://www.tcpdump.org)
 
-[![Build Status](https://travis-ci.org/the-tcpdump-group/tcpdump.svg?branch=master)](https://travis-ci.org/the-tcpdump-group/libpcap)
+[![Build Status](https://api.travis-ci.com/the-tcpdump-group/libpcap.svg?branch=master)](https://travis-ci.com/github/the-tcpdump-group/libpcap)
+[![Build Status](https://ci.appveyor.com/api/projects/status/github/the-tcpdump-group/libpcap?branch=master&svg=true)](https://ci.appveyor.com/project/guyharris/libpcap)
 
-[![Build Status](https://ci.appveyor.com/api/projects/status/github/the-tcpdump-group/tcpdump?branch=master&svg=true)](https://ci.appveyor.com/project/guyharris/libpcap)
-
-Now maintained by "The Tcpdump Group"
-
-  https://www.tcpdump.org
-
-formerly from 	Lawrence Berkeley National Laboratory
-		Network Research Group <libpcap@ee.lbl.gov>
-		ftp://ftp.ee.lbl.gov/old/libpcap-0.4a7.tar.Z
-
-To report a security issue please send an e-mail to security@tcpdump.org.
+**To report a security issue please send an e-mail to security@tcpdump.org.**
 
 To report bugs and other problems, contribute patches, request a
-feature, provide generic feedback etc please see the file
-[CONTRIBUTING.md](CONTRIBUTING.md) in the libpcap source tree root.
+feature, provide generic feedback etc please see the
+[guidelines for contributing](CONTRIBUTING.md).
 
-The directory doc/ has README files about specific operating systems and
-options.
+The [documentation directory](doc/) has README files about specific
+operating systems and options.
 
 Anonymous Git is available via:
 
@@ -36,7 +26,14 @@ require this functionality, we've created this system-independent API
 to ease in porting and to alleviate the need for several
 system-dependent packet capture modules in each application.
 
-For some platforms there are README.{system} files that discuss issues
+```text
+formerly from 	Lawrence Berkeley National Laboratory
+		Network Research Group <libpcap@ee.lbl.gov>
+		ftp://ftp.ee.lbl.gov/old/libpcap-0.4a7.tar.Z
+```
+
+### Support for particular platforms and BPF
+For some platforms there are `README.{system}` files that discuss issues
 with the OS's interface for packet capture on those platforms, such as
 how to enable support for that interface in the OS, if it's not built in
 by default.
@@ -44,18 +41,10 @@ by default.
 The libpcap interface supports a filtering mechanism based on the
 architecture in the BSD packet filter.  BPF is described in the 1993
 Winter Usenix paper ``The BSD Packet Filter: A New Architecture for
-User-level Packet Capture''.  A compressed PostScript version can be
-found at
-
-  https://www.tcpdump.org/papers/bpf-usenix93.ps.Z
-
-and a gzipped version can be found at
-
-  https://www.tcpdump.org/papers/bpf-usenix93.ps.gz
-
-A PDF version can be found at
-
-  https://www.tcpdump.org/papers/bpf-usenix93.pdf
+User-level Packet Capture''
+([compressed PostScript](https://www.tcpdump.org/papers/bpf-usenix93.ps.Z),
+[gzipped PostScript](https://www.tcpdump.org/papers/bpf-usenix93.ps.gz),
+[PDF](https://www.tcpdump.org/papers/bpf-usenix93.pdf)).
 
 Although most packet capture interfaces support in-kernel filtering,
 libpcap utilizes in-kernel filtering only for the BPF interface.
@@ -70,22 +59,21 @@ BSD, and macOS; an older, modified and undocumented version is standard
 in AIX.  {DEC OSF/1, Digital UNIX, Tru64 UNIX} uses the packetfilter
 interface but has been extended to accept BPF filters (which libpcap
 utilizes).  Also, you can add BPF filter support to Ultrix using the
-kernel source and/or object patches available in:
-
-  https://www.tcpdump.org/other/bpfext42.tar.Z
+kernel source and/or object patches available
+[here](https://www.tcpdump.org/other/bpfext42.tar.Z).
 
 Linux has a number of BPF based systems, and libpcap does not support
 any of the eBPF mechanisms as yet, although it supports many of the
 memory mapped receive mechanisms.
-See the [README.linux](doc/README.linux.md) file for more information.
+See the [Linux-specific README](doc/README.linux.md) for more information.
 
-Note to Linux distributions and *BSD systems that include libpcap:
+### Note to Linux distributions and *BSD systems that include libpcap:
 
 There's now a rule to make a shared library, which should work on Linux
 and *BSD, among other platforms.
 
-It sets the soname of the library to "libpcap.so.1"; this is what it
-should be, *NOT* libpcap.so.1.x or libpcap.so.1.x.y or something such as
+It sets the soname of the library to `libpcap.so.1`; this is what it
+should be, **NOT** `libpcap.so.1.x` or `libpcap.so.1.x.y` or something such as
 that.
 
 We've been maintaining binary compatibility between libpcap releases for