[ticket/12240] Added specific class name to posting buttons

PHPBB3-12240
[ticket/12240] Added class code for custom bbcodes based on bbcode_tag

PHPBB3-12240
[ticket/12240] Added template changes for subsilver2, too

PHPBB3-12240
[ticket/12240] fontsize => size; fontcolor => color and added bbcode- in96

PHPBB3-12240
Merge pull request #2074 from Crizz0/ticket/12240

Ticket/12240 - Adds specific class to BBCode-Buttons in Template incl. Custom-BBCode support