Bump libgit2 to v0.19.0
Fix install.js verbiage
git_indexer_stats -> git_transfer_progress
Use git_direction
Libgit2 changed/renamed some APIs
Download progress -> callback
Compile libgit2 with -fPIC
git_remote_add -> git_remote_create
Remove `packed` property from reference
Convert fetch- and push-specs to arrays
Provide converter for filemodes
Remove reference.packed from test code