Fix downcasting warning in oiiotool.
Use "long long" as the type for memformat.

off_t is always 32-bit on MSVC; the implementation was using "long long" already.
Use native path separators in the filesystem unit test
Fix unused variable warnings.
Fix the default font name for Windows.

The "Courier New" font is in the %SYSTEMROOT%\Fonts\cour.ttf file.
Use the two digit exponent format in oiiotool globally.
Minor white space fix.
Remove superfluous CMake option.

CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS was used for CMake 2.4.x compatibility, but OIIO requires CMake 2.6. See:
http://www.cmake.org/Wiki/CMake_FAQ#Isn.27t_the_.22Expression.22_in_the_.22ELSE_.28Expression.29.22_confusing.3F
Fix double to float cast warnings in the RGBE plugin.
Organize the Visual Studio projects in folders.

This changeset organizes the different target projects in folders: "Tools"
(e.g. oiiotool, maketx), "Unit Tests" (e.g. atomic_test, imagebuf_test) and
"Plugins" for the non-embedded plugins. This feature requires CMake 2.8.3,
and it may be turned off by setting the new advanced CMake option
"CMAKE_USE_FOLDERS" (Visual Studio Express does not support folders.)
Use the %SystemRoot% environment variable for finding fonts on Windows.

This should support non-standard installations which use something other than C:\Windows
Fix typo in "oiiotool --pattern" documentation
Fixes and improvements for Windows/MSVC, tested with msvc 2012/Windows 7 and gcc 4.7.2/Fedora 17.

* Pass the strutil and filesystem unit tests.
* Correct default font for oiiotool --text.
* Enable the two digit exponent format earlier in oiiotool, allowing more plugin tests to pass.
* Fix some down-casting warning fixes.
* Added the build option CMAKE_USE_FOLDERS to organize the solution projects in folders.