dejavu-fonts: 2.35 -> 2.37

Release 2.36 adds and fixes a number of glyphes, and adds the
Tex Gyre DejaVu Math font, a companion font to DejaVu Serif for
typesetting mathematics.

Release 2.37 fixes an issue with condensed typefaces.

The sources are now fetched from GitHub, since the development was
moved from SourceForge to GitHub.