First draft of integrated map editor UI
Removed imports pointing to unexistant files (the imported classes were
not even used anyways).
Initial steps for custom tutorials/rooms taken. Can now add custom sign
to room type by adding a tip() function to the specific painter and
placing the sign (see HealthWellPainter as an example). Tutorial floors
also have hardcoded which special rooms appear on them (these specials
will be changed to custom tutorial specific ones as progress is made).
Added logic for specifying/displaying prompts that appear each first
time a specific tutorialroom is entered (only 2 tutorialrooms exist so
far).
Prototype tutorial floor1 complete, half of floor 2 and whole of floor 3
remains (floor 4 will most likely not be customized, except if we can
figure out how to change the ending screen).
Prototype tutorial "complete".
Changed hardhitting room to have skeletons instead of gnoll brutes (the
room was too hard). Also changed positioning for sign in
healthwell/identifywell rooms, since it would occasionally spawn inside
the walls of the room.
Changed some dungeon t_chapters text + created tutorialLevelExit
(advises player to explore whole floor before exiting to the next). 

Contributors: Eric & Özgur
Added missing class.
Minor text changes in tutorial prompts/signs. Also added prompt that
shows first time the player is attacked.
Minor text changes in tutorial prompts/signs. Also added prompt that
shows first time the player is attacked.

Contributors: Eric & Özgur
Merge branch 'eric_test' of https://github.com/QuattroX/pixel-dungeon.git into eric_test
Added prompt for when cursed item is equipped.

Contributors: Eric & Özgur
Fixed some bugs from previous commit.
Added sign that recommends exploring floor fully to the exit rooms of
the tutorial levels.
Minor graphical edits to tutorial icon and tutorial end scene.
Modified readme.
Modified editorui package name so that it is in the same "tree" as the
rest of the packages.
Updated license header with additional contributors in edited/newly
added classes. Also updated about page to explain that this is a mod
etc.
Added placeholder images to make clear that this is a mod (app icon,
title banner). Updated AboutScene for the same reason.