Raptor used to generate resource rsg files in lowercase, regardless what was specified 
in mmp file. That was incompatible with qmake-generated meta data, and caused build errors
for Qt projects in Linux.

So Raptor is changed to generate rsg files case sensitively according to mmp files. 
That could cause build errors on Linux if the case in meta data did not match the real case, 
and people should fix case issues in their source code and metadata, and keep case consistent.

Because this change could stop people building their code, option "--use-rsg-casefolding"
is provided for temparary use, which tolerates case issues so people could continue to build 
their code on Linux before they fixed all of them. However, they should not use this option 
as a permanent work around.

Usage: By default resource files are not case folding, to enable it use option "--use-rsg-casefolding"

This does not affect build on Windows.
