[SVG] Adds clip operator, fixes setGState operator

This PR: 
- Adds support for 'clip' operator (Ref: Default doc) 
- Fixes setGState to accept args properly (Ref: /test/pdfs/extgstate.pdf)
- Added some missing properties for text & path element (Ref: /test/pdfs/text2pdf.pdf)

nit: try to not use method call with different amount of parameters, e.g. make it `this.clip('nonzero')` and if needed use e.g. `this.applyClip('nonzero')`