Make cmake module search case-insensitive.

This is needed to make things like "-f Win32" work, and matches the non-cmake
behavior.

[#276 state:resolved]
Fix a few more cases of case sensitivity in module handling.
Rename -E option to -Z.

"-E" is too easily typoed for "-e", and is dangerous because it overwrites
the following filename.  "-E" is retained as a synonym for "-e".

This change also makes yasm command-line consistent with NASM.
Allow -longopt as well as --longopt.

This is more consistent with other tools.