Fill the alpha channel by default for vcl 32-bit bitmaps too.

Otherwise the alpha channel for bitmaps created directly is empty,
indicating a transparent bitmap (although we don't actually handle
transparency). This complements hardcoding of the alpha channel
in basebmp. VCL bitmaps can be copied bit-for-bit directly into
a basebmp bitmap, hence it's important to make sure we fill the
alpha channel in vcl too.

Conflicts:
	include/vcl/salbtype.hxx

Change-Id: Icb2fa417db6625a6ffa6bd82eb5773ff75be5a3c
Kill gtktiledviewer's alpha channel hack.

basebmp and vcl now set the alpha channel appropriately, so no need
to do so in the viewer now.

However it would perhaps make more sense to just use RGB instead
of RGBA, seeing as the alpha channel is permanently set to be opaque.

Change-Id: I86ad758c6a8bee21b265730727a76605e5850c0c
Remove outdated includes.

These were needed for the X11 "context" rendering which is no longer used.

Change-Id: Ib60c8fff9dad06b1f8f489eed66c3b3c3597e1ee
Implement LibreOfficeKit gtk+ viewer widget.

Very basic, but works.

Change-Id: I0c521e833b53e13065e0be48e6fa767e44b29787
Upgrade gtktiledviewer to use the LOK viewer widget.

Change-Id: Ied397f617d1cad1f3bd095e8af1ffa741916ecca