Moved Display="none" hack & Added .Render check for : if (!Visible ||
!Displayable)

Also, minor change to logic of SvgBoolConverter so bad visibility values
(other than "hidden" or "collapse") wouldn't accidentally hide element

https://github.com/vvvv/SVG/issues/23#issuecomment-25747963

- 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)