add option to convert grease pencil into poly line directly.

Without this, bezier curves at 12 resolution are very high detail for many tasks when converted from freehand strokes.
so add the option to convert 1:1 grease pencil points to curve polygons.

also add use_handles option to curve conversion which is used when converting beziers to poly lines.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55443 954f8c5b-7b00-dc11-b283-0030488c597c