Merge pull request #3 from BruTile/master

Update from origin
Merge pull request #4 from BruTile/master

Merge updates from origin
Use ReaderWriterLockSlim

Improve performance of FileCache by using ReaderWriterLockSlim to get
more concurrency in reading from cache.
Merge pull request #15 from josh-cooley/FileCache-ReaderWriterLock

File cache reader writer lock