Jitter: Change UI. Now use lock icon to indicate relative jitter, tied
to brush size, and unlock icon to indicate absolute jitter untied to
brush size, in screen pixels. Also relative jitter now has soft UI limit
of 2.0 and a hard limit of 1000 times the size of the brush. Should be
enough for the most vivid imaginations...I hope!

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55181 954f8c5b-7b00-dc11-b283-0030488c597c