Story Telling in Dark Shield & graphics update

Finally, Dark Shield has a graphics mode with actual (non-animated) sprites (except for on CLI). Additionally, the world is zoomed in slightly now, making it easier to concentrate on what is going on. This also allows me to later also update the graphics to multi colored tiles and background image tiles. 

I also introduced some more structure to the quests: instead of showing all quests in one message inbox, the quests have now preconditions (e.g. finishing another quest or multiple ones). This allows for much easier creation of long multi-quest stories. As part of that I decided that it should be possible to bundle quests that belong together, so form one coherent story, into one campaign. Since I still have to flesh out about half of the quests in the original campaign I wanted to do, I added an "arcade mode" campaign, called "The Lair". That just allows all environments to be run in one massive quest, similar to how other rogue-likes are just offering one quest, such as "Find the amulet of Yendor and make it out alive.". 

With this release, also some NPCs will yell at you on sight. Some can even initiate an interactive conversation for which I implemented and defined dialog trees. Based on the outcome of the trees, it would be possible to change behaviour of NPCs towards the runner or the environment. However I have yet only implemented this for two NPCs in one quest: the Business Relocation of Act 2. Once the story has been poured into quests more, it will develop into a proper story-driving tool.