extending annotation support

[abhilashsajeev]

There are separate methods to add annotations in annotation_test.go NewLinkAnnotation, NewTextAnnotation.

How about adding other annotations? From the code it is seen that we can add other annotations like Line, Circle etc. It shows in documentation

Could you please provide an example of using AddAnnotationsFile and AnnotationRenderer to create a line at top of all pages in a file?

[abhilashsajeev]

@hhrutter Providing a minimal example to add Annotations other than Link or Text would be really helpful

[hhrutter]

Hi!
I do my best to improve the docs and sporadically add new annotation types as time allows.
What would be the annotation you are most interested in for starters?

Rest assured I am happy to integrate new annotation types as long as they come along with accompanying tests.

[abhilashsajeev]

@hhrutter Adding shapes annotation. Something like a square will be nice

[hhrutter]

The latest commit has support for Square and Circle annotations.
More to come..