minor
Move node revision id retrieving to File constructor
Add LRU cache implementation from <https://github.com/repoze/repoze.lru>
Replace local caches with LRU cache
Move read-only Fuse methods implementation to separate mixin
Fix test hanging in RunInThread
Reset signal handler only if it was set before
Revert "Whitespace cleanup" - for easier merge with other branch

This reverts commit 46a7010ded8d2292a12a00fa0523ea413a0f81e4.

Conflicts:

	svnfs.py
Merge branch 'vrutsky-master'