Doc: new syntax for \tweak, \override (2936) (issue 6852052)

[tdanielsmusic]

Reviewers: ,

Message:
@James
I'm afraid this patch-set will give you conflicts
in changing-defaults with your patch-set 6742057,
but as you "_expect_ to have lots of edits and go
through a few iterations of this" I guess rebasing
it and resolving them (assuming this gets pushed
soonish) will not cause you too much pain.  I think
removing these inconsistencies quickly is important,
but I do apologise for the extra work this will
cause you.

Trevor


Description:
Doc: new syntax for \tweak, \override (2936)

  Also remove text saying spaces are required
  around the . in Lyric overrides

Please review this at http://codereview.appspot.com/6852052/

Affected files:
  M Documentation/learning/tweaks.itely
  M Documentation/notation/changing-defaults.itely
  M Documentation/notation/input.itely
  M Documentation/notation/spacing.itely
  M Documentation/notation/vocal.itely