Merge pull request #689 from 3nids/svgactionicons

use SVG for action icons
Only cleanup python with newer sip versions (Fix #8102)
Followup f3e08b5: Actually clean python on systems with newer sip version
Fix windows build
fix editable attribute of joined fields (fix #7739)
Based on pull request 576 by minorua
more SVG icons
added folder for base SVG images (hammer, pointer, scredriver, etc.)