* `builder_has_action` renamed to `builder_start_action`
* `builder_report` renamed to `builder_finish_action`
* `builder_has_action` created to be a silent test for the action
* Added reasonably comprehensive documentation.
The background reason for this is to test a fix to the web build, where
s.keyman.com resources were not being updated since we refactored the
build configurations (sadly, the build did not die when it should have).
