Support "none" in Fill value if inherited from parent

If elements are nested in groups and have different fill values than
their containing group the fill value wouldn't be written correctly.

When using T, t, S, or s to create curves, the curves were not rendered
properly. The control point was causing the curve to be inverted.

Embedded transformations were not being applied correctly; they were
being done in reverse order.

- Changes to get texts displaying bold / normal weight
- Changes to get textspans work correctly
- Made (semi-hardcoded) document metadata section - allow reading and regurgitating metdata tag from an original source document
- Included image
- Modified paths to allow for scientific notation
- Included ability to have markers for path ends (arrow ends etc)

* fixed missing files

* added few enum converters

* added precise MeasureString method

* added implicit operator from RectangleF to SvgViewBox

* SvgDocument can calculate its size in percentage
* SvgTransform collection can return all matrices multiplied

* added method to collect paths of children elements
* fixed possible bug getinheritedattribute