- convert to maven project
- switch to mbax’ NMS call abstraction implementation
Move base dependencies up, so the project will build in eclipse.
This also improves handling the base dependency, because we only need to change it in one place.

Yes, we want to add those basic .classpath & .project files here - still ignoring it on the other end - to provide maven build + eclipse IDE compiling right out of the box.
- organize some imports/left overs from maven switch
- add NMS fallback code back in again
- optimize NMSManager loading -> disable when fallback code also fails
- remove some unused stuff and make more sense on log outputs
Merge branch 'maven'

Conflicts:
	src/main/java/com/nisovin/shopkeepers/ShopkeepersPlugin.java