Write fill attribute value if it differs from parent element, as a temporal fix.

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.

added nuget information

fixed typo.

One change addresses matrix multiplication order for transformations. The other change addresses the calculation of the control point for smooth CurveTos.

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.

Still a little raw - have a look and let me know what you think

- 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

* fill can be null -> none in XML
* added type converters for enums
* added type converter for unitcollection
* fixes several viewbox bugs
* document can now draw into a given bitmap
* content of SVG tag is written (used by the text tag)
* changed font handling in text element, still need proper alignment
* changed intersparse character of SvgTransformConverter.cs to space, because inkscape couldn't parse comma
* added class diagram for basic shapes