Add outline icons for functions.

[Issue: #369]
Use new function icons in the outline.

[Issue: close #369]
Release notes for v2.1.2
[maven-release-plugin] prepare release Release/2.1.2
Bump ide/ to version 2.1.2
[maven-release-plugin] prepare for next development iteration
Bump ide/ to version 2.1.3-SNAPSHOT