Add HTML support for radio button user values
Add HTML support for radio button user values

Radio buttons select exactly one choice out of many. We enumerate every
radio button and throw out any that aren't checked.

To be consistent with other user-defined values, the value's name is the
ID attribute rather than the name attribute.

icnocop/dotnetinstaller,baSSiLL/dotnetinstaller,baSSiLL/dotnetinstaller,dblock/dotnetinstaller,dblock/dotnetinstaller,baSSiLL/dotnetinstaller,baSSiLL/dotnetinstaller,icnocop/dotnetinstaller,baSSiLL/dotnetinstaller,baSSiLL/dotnetinstaller,dblock/dotnetinstaller,dblock/dotnetinstaller,dblock/dotnetinstaller,baSSiLL/dotnetinstaller,dblock/dotnetinstaller,icnocop/dotnetinstaller,icnocop/dotnetinstaller,dblock/dotnetinstaller