Umbrella Fix

Umbrella's problem all these years was that FindListElem called on a nil
value returns nil, not 0. I fixed that, and standardized its distance
measurement function. It now functions as intended.
$ fix

Fixed nil handling
Removed comment

Removed irrelevant comment
Merge pull request #128 from M59Gar/umbrella

Umbrella Fix
Convert some char * to const char *
Fix some compilation problems, mostly with const char *.
Fix const char * compilation
char * -> const char *
Merge branch 'master' of https://github.com/Meridian59/Meridian59
Merge branch 'master' of https://github.com/Meridian59/Meridian59