Potential replacement for QSettings. This database will allow us to save
settings incrementially, removing most of the performance issues we're
having when our few megabytes of settings are being saved.
Not done in the form of a QSettings backend because it doesn't seem the
backends can do an incremental update of the settings.
Currently used by the QuickOpenPlugin for testing.
Task: 241959, 248085
RevBy: Optics/Naming checked by con
Details: Give IOptionPage an id() to differentiate from trName(). Make showOptionsDialog return a bool (applied) and give it an optional parent. Change Cpp and form class wizards, give them a Configure... button to change those settings.
The previous interface wasn't sufficient to properly support the Apply
button, since it didn't separate applying the changes from the cleanup
phase.
Designer settings pages still need some fixing.
Fixes Apply button causing problems for certain plugins, for example the
QuickOpen.
