new features, bugfixes and more code rework progress

* CODE: Changed main form's tabcontrol to a panel with a label. Visually
should remain the same.
This is because with TabControl, there's flickering on child controls no
matter what you do! While this way, at least there's no flickering when
changing horizontal size.
* CODE: Forms are now properly closed at all times except when closed by
user's choice.
This is better than before because this allows forms to close properly
on all sorts of events - task manger's close, windows shutdown, etc.
All forms are now Owned by Main Form, and thus when MF is closed, all
other forms get closed as well.
* Fixed a bug with upgrading settings file to a new version (that nobody
should have ever encountered since settings version was last updated
very long ago)
* Cosmetic fixes in the "Find" menu: Replace had no ellipsis, Next and
Previous were not capitalised, and Previous was shorted to prev. for
some odd reason
* All forms (except the main form and dialogs) are now shown above the
Main Form at all times, so that they do not get lost behind the Main
Form
* All forms (except the main form and dialogs) can now be made
transparent when they're not active
* Notepad form was added, so that the editor does not demand you to
paste anything into a text editor of your choice, but rather shows it to
you immediately
* Dependency form is now properly opened with "Open dependency form"
option (Shift + F4) even for the first time (before it would not open
unless you at least once open it "for current node")
* You can now define what player ship names you want to have as default
options for create statements (and there is now a list of 8 by default)
* New feature: finding problematic places in the mission script. This
will allow you to find subtle things like names not matching up or
conditions possibly leading to weird results.