Revision 468474

usecase handler cleanup.

[1] remove all cforms-specific code from usecases.js and
UsecaseView.java
[2] split usecases.js into maintainable chunks
[3] introduce a mechanism to add custom flow code (see javadocs in
UsecaseView.java and read usecases.js for details)
[4] remove DummyCFormsUsecase.java and cforms-specific usecases-utils.js
from global code
[5] add CForms.java usecase to cforms module
[6] add custom flow to cforms module to restore functionality
[7] tweak bxe usecases to not create continuations (this restores their
original behaviour which was changed by the previous revision of
usecases.js)

HEADSUP: cforms saving is currently broken, and there is instrumentation
code left in modules/cforms/flow/customFlow.js.