disk access caches allow concurrent lookups / loads.

Previously, if one loaded a file (LUT) that wasnt in cache, this would block
concurrent access of the file caches, even for different files.  With this
update, lookups for *different* files are non-blocking. However, lookups on
the same file *are* blocking; a lut should never be loaded twice from disk even
when concurrently used.

This change was added so image viewers which need real time performance can
efficienly use a 'prefetch' thread to see the file caches ahead of time. This is
particularly useful when used when playing clips with per-shot 3-D LUTs.
Update test to detect incorrect base usage in ApplyLinToLog, correct the bug
Remove use of seekg in CSP support to prevent an msvc10 bug with 64 bits build
Merge pull request #310 from malcolmhumphreys/master

pyglue refactor and test suite
* removed includes for missing PyConfig.h in PyConfig.cpp and PyMain.cpp