Gen popup impl. #13 (major)

Major update;
* Implementation of generic widget implementation appears to function OK
* All other popup implementations still fail (row, page, etc.)
* Upgraded code; all places in nxsfunction that caused a "die", now use
the webmethod_return_nack
* More clear stacktrace and parameters for debugging in
webmethod_return_nack
* Updated row icon
* Fixed bug in contextprocessor extension
* Introduced a new (third) JS variable to hold important state; the
nxs_js_popupsessioncontext; its a contains that holds generic state
information required to render popups. Instead of making compound values
(widgets_1_a235235_2) we can now use strong typed parameters.
* Cleaned up messy code, and using robust parameters between client -
server (major improvement)
* ContextProcessor now is responsible for determining what to do when
generic popup is saved.
* Client side code now invoked startnewcontext() to start a new context.
This wipes both the context and data connected to the context.
* System no longer relies on the popup_current_context variable; moved
that one to the context container.
* Prefixed webmethod_return functions (old ones are still in place, but
about to become obsolete/removed)
* Updated function parameters related to generic popups in a great way
* Relies less on extract of parameters; slight speed / mem optimization
* Fixed optiontype bugs in items to be extended