XSLT HTML Improvements: Image & List alignment, Columns in Frames, SVG Basics

[svanteschubert]

Started small, should been kept small, but but took me four days in total (two days on SVG)

Commits

1. Adding some comments on SVG functionality
2. New feature Adding basic ODF Draw to SVG functionality in XSLT and resulting new reference HTML files
3. Adding some test files for Draw to SVG
4. Fixing style:family prefix for unique style ID in CSS in case of multiple style attributes at draw:frame (i.e. draw:style-name and draw:text-style-name)
5. Fixed List Alignment tdf95662 Enabling @left:margin for list label based on its fo:text-indent value (usually negative value)
6. tdf95662 Enabling text:tabs also for the paragraph style property @Style:tab-stop-distance
7. tdf95662: Complex-Multi-List-Level testODT: The attribute @text:display-levels determing how much list levels are being shown was wrong interpreted and is now fixed
8. ListLevel had been wrong incremented in the recursion (should only be recalculated with every match of a new text:list-list) and in addition the ListLevelStyle - the style according to current listLevel is now correctly kept in synch!
9. Fixing previous regression of duplication of 'cm' for list margin
10. tdf95662 - removed duplication of list suffix/prefix for numbered lists
11. Adding improved test documents for tdf95662
12. Adding multiplier for min-height and max-height in case of columns, as height is divided among columns in HTML/CSS and has to be multiplied by column count to adjust back to ODF height
13. New feature Adding columns by styles for frames
14. **Fixed Text flow around Images ** Adding alignment='middle' to images being used as character (with @text:anchor-type='as-char')
15. Adding margin of list to HTML/CSS
16. Adding z-index to HTML/CSS output
17. Fixed Image Alignment Fixing image horizontal alignment with LEFT=> float:left;position:relative; and CENTER=> display:block;margin-left:auto;margin-right:auto; and RIGHT=>float:right;position:relative; and vertical alignment using top: XYcm;position:absolute;
18. Adding image alignment test case
19. Making half a dozen class style names unique by adding the family name in front

[svanteschubert]

• New feature: Added polygons to the SVG export!

This PR is now ready and can be reviewed and merged.
Many thanks in advance, Michael! 👍