Added optimization option

[andreeapetian]

Added new option for optimization level: optimize aggressively for size

[ilg-ul]

Could you rename the option option.optimization.level.size.aggressive?

[ilg-ul]

Please also add this option to the riscv.core plug-in.

[ilg-ul]

It seems ok.

There is a small remaining detail, please make your patch against the develop branch, since I have to test it before making the final release.