Text: improve AbstractFont documentation.
Text: test line advance behavior when rendering scaled text.

Currently the test fails, because line advance doesn't take text size
into account.
Text: fix rendering of scaled multi-line text.

Take text size into account when advancing lines. I would probably not
run into this issue if I would visually test this on anything else than
unscaled pixel art font.
Text: minor cleanup.
Text: harden and clean up Renderer test.
Text: test that proper index type is used in Renderer.

Something smells fishy here.
Text: it's totally fine to have 256 vertices indexed with UnsignedByte.
Text: fix array index type in Renderer.

When we have 256 vertices and >256 indices, we need more than 8 bits to
index the index array. The tests are passing again.
Added colour uniform to flat shader (event when texturing is enabled)
This enables blending and transparency
Default colour is white (and fully opaque)
Use "" instead of <> for inter-project includes.
Merge branch 'master' into compatibility
GCC 4.4 compatibility: some explicit typing is needed.
GCC 4.4 compatibility: work around ambiguous constructor.

That thing added its own variant of copy constructor and then complains
that it is ambiguous with the other.