Tear out most of the legacy code in the PC editor - see below for details

(Scenario Editor is unaffected by this commit.)

- Menubar converted to a .xib file
- Don't include the Info.plist in "Copy Files" stage
- Several more dialogs converted; as before, the source resources have had their resource name changed to the new filename
- One more converted STR# has been included

There were several functions in the PC Editor code that also existed in the BoE game code. I've moved these into the pc.editors.cpp file, so that there's only one copy of each.
- display_alchemy() functions changed signatures
- moved keyToChar() function into a common file (winutil)
- Several constants and globals moved to pc.editors.cpp

Supporting changes to dialog framework:
- New formatting option to set the frame style; this because the PC editor uses a different frame style in some contexts
- Added global default dialog background setting
--> This was necessary to correctly set the default text colour
--> Will also be needed for the scenario editor, which uses a different default background

Other changes:
- Add option to load_scenario to skip loading the strings
- Fix for crash in soundtool in the event of initialization before playing the first sound

rsrc/dialogs/edit-xp.xml

@@ -0,0 +1,16 @@
+<?xml version='1.0' encoding='UTF-8' standalone='no'?>
+<?xml-stylesheet href="dialog.xsl" type="text/xsl"?>
+<dialog skin='dark' defbtn='okay'>
+	<field name="number" type='num' top='127' left='216' width='75' height='16'/>
+	<pict type='dlog' num='2' top='8' left='8'/>
+	<text size='large' top='8' left='49' width='209' height='16'>Changing experience:</text>
+	<text top='27' left='49' width='288' height='67'>
+		Enter how much experience you want this character to have.
+		Note that the character will not gain any more levels until the character earns at least 1 point more point of experience in the game.
+		The most you can give is 10000.
+	</text>
+	<text name='perlevel' top='99' left='72' width='164' height='16'>Experience for each level:</text>
+	<text framed='true' top='99' left='238' width='76' height='16'/>
+	<text top='127' left='72' width='138' height='14'>Amount of experience:</text>
+	<button name='okay' type='regular' top='154' left='270'>OK</button>
+</dialog>