Remove dead code.
style
Check in case the cursor's current node is NULL.
Don't need to check for null here. free(NULL) is okay, bro.
Small improvements to cursors and _ol_is_enabled.

- Fixes a bug zeroZshadow pointed out in regards to feature checking
- Cursors now fail to initialize if splay trees aren't enabled.
Fix travis failure.
Merge branch 'master' into mmap_redo
Refactored some things out of ol_database into ol_meta.

- Removed hashes_fd because I won't be needing it. mmap() duplicates the
  file descriptor it is given.
Fixes bug when debug is enabled.