Implemented cached file lifetime in MaplyRemoteTileSource, fixed typo.
Merge pull request #163 from capncode/master

Implemented cached file lifetime in MaplyRemoteTileSource, fixed typo.
Accidentally merge changes into the main tree.  Reverted.  Also fixed a few recent compile problems.
Accidentally merge changes into the main tree.  Reverted.  Also fixed a few recent compile problems.