[trunk] Generalized dependency checking in Native C builder code to pick up any file to be created
[trunk] Make sure specifying source files come through as files that exist
[trunk] Filtering locations only return those that are valid
[trunk] Only write out QMake variables for the destination directory when it exists. It may not, if only compiling code
[trunk] Support linker map file creation through Locations. Support VisualC compiler per-object file PDB through Locations. Code cleanup
[trunk] WIP code tidyups