Fixes truetype font generation. The Glyph coordinate generation
had some issues for fonts which have characters drop well below
the baseline.

Adds 'Goudy Bookletter 1911' test font.
The truetype test now renders the same string multiple times
at different scale factors. Once for each of two truetype fonts.
Adjust truetype loader.

The manual adjustment of a glyph's height is a hack which
should be fixed at some point. It is unclear how to obtain
the correct glyph height at this point.
Adjust truetype loader again.
Amend README's Known Bugs list.
With thanks to +Komiga, the power-of-two scale factor issue
for raster fonts has been fixed.
Add Time Howard (komiga) to CONTRIBUTORS file.
Fixes README.
Removes all graphical tests. These are now available as example
programs at github.com/go-gl/examples/text
* Implements Font.Metrics() method. It computes the pixel width/height
  for a given (multi-line) input string by using glyph sizes and
  advance values. Font direction is taken into account.
* Adds Font methods which return some of the FontConfig field
  values, so they may be accessed by callers.
* Removes unused code.
Removes TODO item about font metrics from README.
Applies minor refactoring and adds more bug notes to the README.
Fixes code comment to include pixel format for supported raster
font images.
Changes Font.Metrics to assume input text is a single line.
None of the other Font related operations work on multi-line text,
so neither should this one for consistency.
Fixes README to refer to correct examples path.
Merge pull request #2 from jteeuwen/master

Fixes for README
Adds a note about Valve's 'Signed Distance Field` techniques to render
font textures at various zoom factors. This may be worth looking
into at some point.
* Removes some utility functions from misc.go. These have been
  added to the go-gl/glh API.
* Removes test file for misc.go. It is no longer applicable.
Adds a note about GLyphy to the README.
Fixes call to gl.MultMatrixf to use fixed-size array instead
of a slice.
Merge pull request #4 from jteeuwen/master

Fixes call to gl.MultMatrixf