small whitespace fix
removed not required options variable; some other small improvements
changed admin about page menu slug; some other small class changes
removed not used group variable in options class
merged 2 $out lines
added check if given comment_callback_function exists
fixed regex in truncate function

The old version didn't match the h1, h2, ... elements correctly and
caused a wrong </h> closing tag.
show more numbers in pagination
allow different number of rows in textarea options
changed code text size on admin page
added option to specify comment form args directly

issue #23
preparation for version 0.6.3
Merge branch 'develop'