Also removes the unnecessary check for filter
length, since git_filters_apply does the right
thing when there are none, and it's more efficient
than this.
Initial implementation. The relevant code is in `blob.c`: the blob write
function has been split into smaller functions.
- Directly write a file to the ODB in streaming mode
- Directly write a symlink to the ODB in direct mode
- Apply a filter, and write a file to the ODB in direct mode
When trying to write a file, we first call `git_filter__load_for_file`,
which populates a filters array with the required filters based on the
filename.
If no filters are resolved to the filename, we can write to the ODB in
streaming mode straight from disk. Otherwise, we load the whole file in
memory and use double-buffering to apply the filter chain. We finish
by writing the file as a whole to the ODB.
