Added AnnotationPoints, AnnotationLines
Annotation updates

* Refactored AnchoredAnnotation draw method
  * Annotations now just need to provide draw_annotated()
* Allow text annotations to be scaled when zooming
* Allow points NOT to be scaled when zooming
* Line updates
  * Changed line type (Real,Real,Real,Real) -> ((Real,Real),(Real,Real))
  * Allow user to specify order of point coordinates for
    matrices with four rows
Fixed up font face scaling.
Fix non-scaled point drawing
Fix set_valid, minor rearrangment of annotation.jl
Added documentation for annotations

* This is slightly incomplete, because I haven't tested FloatingAnnotations
Merge pull request #27 from kmsquire/annotation_pts_lines

RFC: Added AnnotationPoints, AnnotationLines