SciDAVis - Improvements SVN-temp

class for Aspects like Table or Notes. Other Aspects may wish to define their
own types of and protocols for views. AbstractPart also handles parts of the
context menu, meaning that it no longer needs to be patched together from two
sources.
- TODO: The new context menus allow columns to be removed from their table via
the project explorer. Some way of updating Table's internal state accordingly
has to be found.
- Added experimental module interfaces. This is supposed to keep the kernel
manageable by splitting out, for example, all table-related code into a
module. Also, after maturing through a couple of releases, these interfaces
may provide the basis of a plugin API.
- Added modular .pro files to go with the module concept.
- Moved creation of undo/redo actions to AbstractAspect in order to avoid code
duplication. TODO: make keyboard shortcuts customizable; probably by using
a Settings singleton for global (i.e., not project-specific) settings.
- Removed "Hide or remove?" question on closing MDI windows.
- Added documentation on the Aspect framework and the 5-layer-model it uses.
Documentation in "related pages" moved to separate files in doc/.
- Some progress made on AbstractFit.