Safely deprecate `git_push_transfer_progress`, forwarding it to the new
`git_push_transfer_progress_cb` name.

The `git_push_transfer_progress` is a callback and as such should be
suffixed with `_cb` for consistency.  Rename
`git_push_transfer_progress` to `git_push_transfer_progress_cb`.

Safely deprecate `git_transfer_progress` and `git_transfer_progress_cb`
types, forwarding them to the new `git_indexer_progress` and
`git_indexer_progress_cb`.

Update internal usage of `git_transfer_progress` to
`git_indexer_progreses`.

The name `git_transfer_progress` does not reflect its true purpose.

It suggests that it's progress for a non-existence `git_transfer`
object, and is used for indexing callbacks more broadly than just
during transfers.

Rename `git_transfer_progress` to `git_indexer_progress`.

Remove public 'inttypes.h' header

Remove an `inttypes.h` header that is too large in scope, and far too
public.

For Visual Studio 2012 and earlier (ie, `_MSC_VER < 1800`), we do need
to include `stdint.h` in our public headers, for types like `uint32_t`.

Internally, we also need to define `PRId64` as a printf formatting
string when it is not available.

`git_time_monotonic` was added so that non-native bindings like rugged
could get high-resolution timing for benchmarking.  However, this is
outside the scope of libgit2 *and* rugged decided not to use this
function in the first place.

Google suggests that absolutely _nobody_ is using this function and we
don't want to be in the benchmarking business.  Remove the function.