Text placement

[tmcw]

No description provided.

[kkaefer]

For now, use the placement information encoded in our custom fontserver vector tiles. For the native renderer, we might eventually switch to using the fontserver code that generates the signed distance fields directly and ship with the fonts in the binary, rather than putting them into the tiles. Also, we're relying on the shaping information encoded in the tiles rather than using harfbuzz/pango directly.

• Extract shaping information from vector tiles
• Create glyph vertex buffer object
• Create style properties that define how to place the text
• Port placement code
• Render the glyph vertex buffer

see #4

[kkaefer]

Tracking in #4