Add "Planet plant" music by jobromedia.

Source: http://secretmaryo.org/phpBB3/viewtopic.php?f=11&t=5053#p31012
Delete all test levels from the official level collection.

As per @sauer2’s suggestion in issue #59.
Fix thromp velocity not being saved
Fix documentation of Std::Enable
Add Convert_Path_Separators() override for boost::filesystem::path
Fix invalid path handling in cStatic.

Invalid UTF-16 conversion for Windows.
Remove outdated compilation line from README