This restores the usage of GIT_DIFF_LINE_BINARY for the diff
output line that reads "Binary files x and y differ" so that it
can be optionally colorized independently of the file header.

This allows git_diff_patch_size to account for hunk headers and
file headers in the returned size.  This required some refactoring
of the code that is used to print file headers so that it could be
invoked by the git_diff_patch_size API.

Also this increases the test coverage and fixes an off-by-one bug
in the size calculation when newline changes happen at the end of
the file.

This adds a new API to get the size in bytes of the diffs in a
git_diff_patch object.

Clarify when to use github issues

git_buf_text_gather_stats doesn't work for multi-byte characters

Suggest that github issues are to be used for bug reports, while questions about usage should be directed to StackOverflow.

Refresh readme and contributing guidance

Updating the contributing guidance to explain a bit more about how we use
PR's

Updated the methods of getting involved with the project and asking
questions.

Switch default calling convention to cdecl

git_revparse_ext: should return a NULL reference  when the revparse expression doesn't lead to a reference

don't include ignored as rename candidates

Small grammar fix in docs

Small fixes

Add `git_remote_owner`.

This reverts commit a91e4d6b.

Fixes return type documentation

Fix #1722

Plug some memory leaks

header files show up in vs and xcode