use roof:lines=no to indicate that possible attached roof:edge/ridge way do not belong to this building part
Merge pull request #52 from hjanetzek/origin

render building outline completely if it has building:parts which is not 'no'
Merge pull request #53 from hjanetzek/roof_lines_no

use roof:lines=no to indicate that attached roof:edge/ridge do not belong to this part
- use roof:height from building:part as default for complex roof
- test if ridge/edge lie on the boundary, pnpoly is not reliable in this case
  - this way single sloped roof can be defined by adding only one ridge on the outline
scale to ground resolution at latitude, then translate to origin
add and use Poly2Tri for roof triangulation