* Make configAccepted() just write the new config, and make configChanged() conditionally update the plasmoid after reading the config back in.
* Split the grid resizing logic into its own method: recalculateGridSizes(int rows), and make it detect more edge cases.
* Rename the main size calculation method to updateSizes(bool allowResize), which will resize the applet to its preferred size if allowResize is true.
* Fix a bug which caused applet resizes to be wrongly cancelled in some situations.
* Code style cleanups, remove unused variables, etc.

(Sorry for putting so many changes into one patch)

Tested configuring the pager from the config interface and the desktop console, and that it responds correctly to changes in desktop count, and in FormFactor and size.