Code cleanup: removed some unused UI button types

* CHARTAB: not needed anymore with improved copy/paste support and text input.
* IDPOIN: replaced by SEARCH_MENU.
* ICONROW/ICONTEXTROW: replaced by RNA enums.
* NUMABS: can use min/max limits instead.
* BUT_TOGDUAL, TOG3, TOGR, SLI: not used in 2.5 interface.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57318 954f8c5b-7b00-dc11-b283-0030488c597c
Fix #35696: cycles crash with no world assigned to scene, after recent changes.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57319 954f8c5b-7b00-dc11-b283-0030488c597c