Prefer fonts with extended characters in FontConfig lookups.

This patch modifies vtkFontConfigFreeTypeTools to return only
fonts that support, at minimum, greek character sets.

Change-Id: I29deb9223df5abbf89502eca643ac51027542cba
Merge topic 'fix_plot3d_issue' into pv-master

0c78697 Fixed user setting were being ignored after first RequestInformation.
Merge remote-tracking branch 'pvvtk/pv-master' into HEAD

* pvvtk/pv-master:

Change-Id: I2705c24459df7b98e81647b2de4f5a8270892378
Merge topic 'font-config-unicode' into master

52e0f169 Prefer fonts with extended characters in FontConfig lookups.