Rendering fixes: delivered as a single commit due to problems merging from a git-svn repository.
Accidentals are now rendered correctly in most cases.
Accidental on a tie at the beginning of a bar is now correctly drawn on the first note.
Tweaked the sparsity setting for layout in an attempt to add a little more horizontal spacing.
Notes are no longer centred within their bounding boxes.
Whole bar rests are centred.
Whole notes are rendered correctly.
Accidental symbols are now larger.
Tweaked noteheads to be slightly larger.
Added glyph scaling.
Made most new rendering behaviour dependent on score-div flags in case it should be turned off.
Improved file chooser for local files (which does not trigger a cascade of dialogs).

Add the following attributes inside <div class="score-div"/> to turn on the rendering fixes.
  whole_note_fix="true"
  larger_accidental_fix="true"
  larger_note_head_fix="true"
  ledger_line_thickness="true"
  ledger_line_width="true"