[WIP] Continuation of redstone support

This will be a continuation of iamgreaser's redstone framework pull request (https://github.com/GlowstoneMC/Glowstone/pull/215), which was closed by him. I think its a very good start for redstone support in Glowstone, so i wanted to continue it.
This is my first pull request, so please say if i did something wrong. (I know i have to merge the branches, but i'll leave that for later)
TODO:
- [ ] Make torches 2-tick not 1-tick
- [ ] Get torches to burn out when flickering
- [x] Redstone placement on slabs
- [ ] Redstone support on slabs
- [x] Redstone block - DONE
- [x] Lever - DONE
- [ ] Pressure plates
- [ ] Buttons
- [ ] Redstone lamp
- [ ] Repeater
- [ ] Daylight sensor
- [ ] Redstone comparator (comparing & subtracting; block state measuring maybe part of another PR)

I think redstone devices like dropper, dispenser and so on should be part of another PR.

I think it is ok to use his commits, since he said it to someone else, that it would be okay.
If not @iamgreaser, please just say it.
This is just used in RSManager to determine if this block should be added to the list of redstone sources to check regulary. Then the traceBlockPowerInit Method checks if this source is powered. And yes, the redstone torch always must be calculated, the reason for that is noted in the traceBlockPowerInit method.