Options; reworked, with fixed footer.

Changes:
   - Added caption "Miscellaneous toggles" to visually separate the
     link-hints checkbox from the others.
   - Made the text for the two link-hint character sets the same.
   - The "Show advanced options" link now spans two columns, so it does
     not affect its column's width, so the layout doesn't change when
     the options below the fold are expanded.
   - Added a fixed footer containing the help text and the save button.
   - The text of the save button now changes when it is enabled.
     (I sometimes find it hard to tell whether its been activated or
     not.)
   - Control-Enter anywhere on the page saves all options.
   - Aligned the entire options table left, instead of centered.  This
     is the chrome style.  However, it also makes it easier to get the
     alignment right between main table and the footer.
   - Change width of main wrapper such that it actually matches the
     table's width.  This aligns the right edge of the bar under the
     title with the right edge of the second column of the table.
Options; Exclusion headers, style fiddles.
Options; Ctrl-Enter blurs active element.
Re-jig options page and re-factor styles
Automatically insert "leave empty" message for nonempty options
Fix the alignment of the save button in options
Align options page help text with the top of the cell
Style tweaks for options page footer
Merge pull request #1248 from mrmr1993/option-for-options-page

Move options page help text to its own cell.

Conflicts:
	pages/options.html
More attractive layout for 'miscellaneous options'