Custom Checkbox and Radio Fields - Configure Options Per Line

Users need a way to configure the display layout for custom checkbox and radio button options. Currently, all options are output inline (with a space delimiter between each option).

1. Configuration (Admin -> Custom Data -> Add/Edit Custom Field:

• add new property to civicrm_custom_field table - options_per_line (int, nullable)
• add new input field which displays only if html_type = Checkbox or Radio
  -+ label = Number of Options Per Line

2. Edit/View Custom Data (contact/view/cd AND user/register + user/edit profile forms)

• if options_per_line for the field is > 1, generate a table layout for the field options with $options_per_line cells per row and a checkbox element + label in each cell.

Example: If options_per_line = 3, and I have 5 options, the layout would be -
<dt>Field Label</dt>
<dd>
<table class=form-layout><tr><td><input type=checkbox.../> Red</td><td><input type=checkbox../> Green</td><input type=checkbox ../> Blue</td></tr><tr>...2nd row with remaining 2 options ...</tr></table></dd>

NOTE: Currently we use the Quickform addGroup function to insert a set of checkbox or radio options into a form. As far as I know, this function only supports passing a single option separator (e..g '<br />', or ' '). So we may need to bypass this function and generate the table layout in the tpl (as I think we have done for the checkboxes which are listed in the scrolling divs for Search -> Select Group ...).