gfx-glyph-0.13.2

• Optimise vertex updating by declaring 'Dynamic' usage & using explicit update calls.
• Add GlyphBrush::queue_pre_positioned and example pre_positioned.
• Add SectionGeometry, GlyphPositioner to glyph_brush re-exported types.
• Update glyph_brush -> 0.3.

With the glyph_brush update it may be possible that some usage is broken, however I think it unlikely enough to make this a non-breaking release. Please get into contact if this breaks your usage.