SMF-Garage v2.3.1

Fix warning "Undefined index: exec_disabled".
Replace some deprecated functions.
Remove redundant closing tags.
Fix parameters number mismatch declaration.
Replace obsolete mysql_result functions.
Replace split with preg_split functions.
Reformat source code for compliance PSR-1/PSR-2 coding standards.
Better mod structure. Some installer improvements.
Version 2.3 updated by margarett. Removed support for SMF 1.1.x. Removed upgrade options from ancient versions. Fixed installer to work with 2.0.9+ and some file locations (scripts and CSS).