Made the first option of a radio button group the default value if no value is given, mirroring the way a <select> element works.

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2824 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7
Fixed bug in last change

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2825 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7