Fix compiling with clang

Expose JavaScript function name in a rejected promise

fix issue with re-require()'ing native modules

Generate default options for Revert.revert to prevent an exception

Due to the way the C++ binding layer gets the promise callback passed
to it, if there are no options specified in Revert.revert, the
promise callback ends up becoming the third parameter to the function
and the expected fourth parameter will not be satisfied which will
lead to an exception. We should generate a default options for
Revert.revert if nothing is provided by the callee to make the API
easier and simpler to use.
Signed-off-by: Remy Suen <remy.suen@gmail.com>

When an error happens in libgit2, NodeGit will wrap the and expose
the error code and message to be consumed via the JavaScript API.
However, this information is often insufficient given the
asynchronous nature of NodeGit and it may at times be unclear as to
which JavaScript function caused the error on the libgit2 side. By
exposing an 'errorFunction' property string that includes the name of
the JavaScript function in the error, debugging should now be a lot
easier as clients will now be able to quickly identify which
JavaScript function in a long promise chain was the source of an
error.
Signed-off-by: Remy Suen <remy.suen@gmail.com>

Updated descriptors for git_index_find and git_index_find_prefix

Updated input docs to allow for git_push_update_reference_cb to  generate

Added a better normalizeOptions pattern for the submodule update routine

Bumped libgit to libgit-next head

Fixed an issue where large buffer allocations in filters (> 256MB) causes a segfault

8.4.0 currently breaks builds, locking to 8.3.0 temporarily

Fix git_tree_entry double free

BREAKING: Added blob methods and converted to async

BREAKING: Convert sync methods to async methods