lol namespaces
merge!
renames!
move NAME and REUC extensions to sys/
Merge pull request #1523 from libgit2/vmg/namespaces

Namespace support
Merge pull request #1389 from ethomson/merge_trees

Merge trees
refdb: Proper namespace root
merge: Warning noise
allow empty dirs to exist when doing checkout
refdb: Properly load namespaces
Merge pull request #1527 from ethomson/checkout_allow_empty_dirs

allow empty dirs to exist when doing checkout
Add extra locking around packfile open

We were still seeing a few issues in threaded access to packs.
This adds extra locks around the opening of the mwindow to
avoid a different race.
Extra threading tests

We need to hammer the packfile open phase harder in the thread
tests, in addition to the cache API.
Fix some compile warnings and trailing whitespace
Protect sha1_entry_pos call with mutex

There is an occasional assertion failure in sha1_entry_pos from
pack_entry_find_index when running threaded.  Holding the mutex
around the code that grabs the index_map data and processes it
makes this assertion failure go away.
Merge pull request #1529 from arrbee/more-packfile-locking

More packfile locking
refdb_fs: do not require peeled packed refs to be tags

Older versions of git would only write peeled entries for
items under refs/tags/. Newer versions will write them for
all refs, and we should be prepared to handle that.
Revert "Protect sha1_entry_pos call with mutex"

This reverts commit 8c535f3f6879c6796d8107d7eb80dd8b2105621b.
refdb_fs: implement the fully-peeled trait
refdb_fs: store "cannot be peeled" flag for packed refs

Fixes #1532