New targets (Debug, Release, Final, Shrinkler). [updated to 1.6.8]

[davidcanadas]

This PR provides replaces built-in targets AROS, A500, A1200 and A4000 with more specific targets:

Release

• Default target used when compiling with Ctrl+Shift+B.
• Defines the DEBUG macro.
• Enables optimizations which may render some code not debuggable.
• Additional GCC/GAS options: -gdwarf-3 -Ofast -DDEBUG.
• Additional VASM options: -dwarf=3 -DDEBUG.

Debug

• Defines the DEBUG macro.
• Disables all optimizations. Code is debuggable at the cost of losing some performance.
• Additional GCC/GAS options: -gdwarf-3 -DDEBUG.
• Additional VASM options: -dwarf=3 -DDEBUG.

Final

• Makefile targets this by default.
• Same as final but enables macro NDEBUG instead of DEBUG to provide some sort of stripping at the source code level.
• Additional GCC/GAS options: -gdwarf-3 -Ofast -DNDEBUG.
• Additional VASM options: -dwarf=3 -DNDEBUG.

Shrinkled

• Same as Final but shrinkles the executable using the new option amiga.shrinkler.options in the Settings page.
• The executable launched in the emulator is the shrinkled one (which is renamed to the name of the program).
• Symbol stripping still has to be done using the -s parameter when calling elf2hunk.
• Shrinkling is done by an external file mkfinal.bat.

Potential improvements:

• Splitting Shrinkled into two targets, one for profiling (which includes DWARF information) and one for publishing (not including DWARF information + calling elf2hunk with parameter -s).

Related to: #52
Replacement for #127 (which became outdated).

PS: This is my last Pull Request for now :) (It's the only actual difference between the extension and my fork). Maybe is too specific and out of the scope of the template, however it is worth the try!