Switch uninstall to 'pre_uninstall' hook.

Since the module is still installed when the hook is called, the module helper can be used reliably. This change, in addition to previous changes, resolves #17
hide security test file
Merge pull request #178 from alain91/branch120

hide security test file
Merge pull request #177 from geekwright/issue17

Comments and notifications module uninstall actions
Move class/xoopsform classes to Xoops\Form namespace

* class/xoopsform classes become backward compatibility stubs
* all logic is in Xoops\Form namespace classes
* minor changes to Xoops class
* system is using BC stubs, updates to namespaces will be phased in

In general class names are similar to original name, i.e. XoopsFormDateTime becomes Xoops\Form\DateTime. Exceptions were made to normalize naming, remove abbreviation, etc. Stub functions serve as a cross reference of old to new class names.
Some fixes related to namespaced form changes
Merge pull request #179 from geekwright/forms

Move class/xoopsform classes to Xoops\Form namespace
Convert system module to namespaced forms

plus a few other related fixes
Fix accidental edit
Minor clean up
More fixes
Merge pull request #181 from geekwright/forms2

Convert system module to namespaced forms