Add qtcsv.qbs for easier inclusion in QBS based Projects

[MaAbt]

No description provided.

[iamantony]

Hello, @MaAbt !

Thanks for your contribution!

Well, I never used .qbs files so I don't know much about them. But I have a few comments:

• in .qbs file you set that we build static lib, but qtcsv by default is shared lib. Could you add a commented command or a special flag that would switch build type from shared to static? (Examples: qtcsv.pro, CMakeLists.txt). And also QTCSV_STATIC_LIB define should be added only in case of building of static lib.
• qtcsv do not requires C++11
• could you add a version of qtcsv?
• could you add compiler flags for gcc? (Example: CMakeLists.txt)
• could you add installation command?