Added pre de/increment operators. Fixed post de/increment operators

Follow-up to c18f438

Signed-off-by: Haru <haru@dotalux.com>
Fixed some outdated script debug functions

Signed-off-by: Haru <haru@dotalux.com>
[WIP - TO BE REBASED] Documentation update - added operators info
[WIP - TO BE REBASED] Removed pointless '~=' operator
[WIP - TO BE REBASED] Corrected operator precedence table

NOTE: Scripts WILL break, especially if they use bitwise |, &, ^, since their precedence was completely incorrect.  They need to be checked
[WIP - TO BE REBASED] Self-test script
[TO BE REBASED] added support for automatic concatenation of adjacent string literals (thanks to Trojal for the idea)