Drawj2d 0.6.0 released

This release adds statics commands and TeX typesetting enhancements.

Forces are defined by their application point and force vector: "x y Fx Fy". The stat.* commands are related to forces, but they are not drawing commands. Use the commands force and force2 to draw forces.

Changes related to forces:
- new commands FX, FY, XY, FXY. Returning force components, application point or vector.
- new command fu/kN returning the force length in drawing units.
- new commands stat.add/+++, stat.subtract/---, stat.multiply/***. These commands respect equilibrium.
- new commands stat.abs, stat.distance, stat.moment
- new commands stat.move and stat.move2
- new command stat.actionline
- new command stat.mequi for moment equilibrium
- new command stat.fequi for force component equilibrium
- new command stat.equi for (general) equilibrium
- drawing commands force and force2 enhanced

Other changes:
- new commands geom.extend, geom.distance
- new commands texdimline, texdimlineto, texdimlinerel, texforce, texforce2. These are equivalent commands to dimline, etc. but using TeX typesetting (built-in jlatexmath).
- command here enhanced