Tip of the day feature

[prmr]

Document the key features of JetUML as documentation modules (a.k.a. "tips"), that can be viewed one by one when the tool starts, or as a whole from the help menu. A user preference should determine whether tips are shown upon startup.

Each tip should correspond to one cohesive piece of documentation about the tool. Tips should be stored as resources, and comprise at least one block of mark-up text and optionally one image. It should be possible to generate an indexed documentation page by using the documentation.

The documentation modules should have a sequence index. The JetUML properties should remember the last module seen by the user.