Bugfix: org-dotemacs-load-blocks only print messages if necessary

Check that evaluated-blocks, unevaluated-blocks and unmet-dependencies are
non-nil before printing associated messages.
Also add org-dotemacs to beginning of all messages.

Altered items:
org-dotemacs-load-blocks, org-dotemacs-load-file
Make org-dotemacs-error-handling customizable

Also add ERROR-HANDLING arg to org-dotemacs-load-file,
move code for handling command line arguments to the end of the file
and added more documentation.

Altered items:
org-dotemacs-error-handling, org-dotemacs-load-file
Change customization group to org-dotemacs
Update documentation

Also change name of errorhandling arg to error-handling

Altered items:
org-dotemacs-load-blocks