v2.2.1.2 Released

I have tagged v2.2.1.2. This is a bug fixing release.

A few important bugs have been fixed since v2.2.1.1:

1. Accurate arc rendering (Issue #2035). The Qt rendering framework doesn't accurately render arcs(and elliptic acs) when zoomeded. This issue was identified and fixed for arcs in v2.2.1.2;
2. A crashing issue (Issue #2034);
3. A few usage issues.