## Source file scoping
Source files are assigned a scope of either FPM_SCOPE_LIB, FPM_SCOPE_APP or FPM_SCOPE_TEST.
The scope controls which modules may be used by the source file:
- Library sources (FPM_SCOPE_LIB) may only use modules also with library scope.
 This includes library modules from dependencies.
- Executable sources (FPM_SCOPE_APP,FPM_SCOPE_TEST) may use library modules (including dependencies)
 as well as any modules corresponding to source files in the same directory
 or a subdirectory of the executable source file.