Fix width measurements and accelerator handling

Change-Id: Ide0a5aee6c524830372c8967cfd35696679e8930
Improvements to pango code

* improve accelerator handling
* improve end-of-line whitespace trimming (still needs some work,
  but it should be about the same as the cairo renderer now)
* vertical text support
* clipping more consistent with MS GDI+
* better bidi text support
* string trimming closer to MS GDI+
* tab stops (untested)
* better bounding boxes returned (taking into account ink and logical
  space)
* support for codepointsFitted in MeasureString
* better linesFilled support in MeasureString
* NoWrap will still wrap on newline (MS GDI+ does this)

(Latest patch derived from email message at
http://software.1713.n2.nabble.com/libgdiplus-pango-patch-td2268439.html)

Change-Id: Ib2e5b70b66a4524f5b931a2de0a04c3674b629fc
Fix problem with pango measure string

If the height is 0 or MaxInt it means any height. This change fixes
the problem where we didn't deal with MaxInt properly, resulting
in a string width of 0 being returned.

Change-Id: I41880c9312e0b765bcc0f86e1cd8c151fba80100
Fix height calculation in pango setup layout code

If we get called with a frame height of 0 we should use whatever
height it takes. The MWF code calls us with both 0 and MaxInt to
get the required height.

Change-Id: I8129e32f88e7daad6126950a6a7b30c730ed0400