Fixes CR_DEVOTION and MG_STONECURSE behaviour, hiding behaviour.

Fixed CR_DEVOTION to not be casted on other characters while the limit is already reached. Follow-up: e7be72538ea9c203bfd7a976d82e268e04303ca4

MG_STONECURSE now correctly displays effect when terminating SC_STONE. No longer works on hidden characters. Bug report http://hercules.ws/board/tracker/issue-7958-stone-curse/
Hiding no longer prevents skills from working if they were casted before hiding and are not intended to inflict damage (buff/de-buff skills). Tested on aegis.
Merge pull request #339 from csnv/skillchecks

Fixes CR_DEVOTION and MG_STONECURSE behaviour, hiding behaviour.