make precompiled header slimmer under Linux to increase CI and dev-machine build-times
make sure unused modules don't compile
add unused modules to the VS project to easier keep track of them
* Improved image decoding modules:
- Fixed error that appeared after last commit (eebe859f83).
- Changed some functions to use the mem*_t classes.
- Implemented cell*DecSetParameter.
* Created new dummy modules for sys_net (0x0000), sys_http (0x0001),
cellHttpUtil (0x0002) and cellSsl (0x0003).