Make blocks outside of initial chunk "editable"

[bbarker]

Currently cannot select them due to hardcoding of '16' in GameState#calculateSelectedBlock. When outside of the initial chunk, placement of blocks also seems to be off-by-one; likely related to #8.

[bbarker]

In this issue branch, they appear to be editable now in general, but:

Not all faces of a placed block appear to create collision outside of origin chunk - in fact, they are different

• [ ] Removed chunks are not rendered outside of the origin chunks.
• [ ] (-1, 0) chunk: only the outer face in the -x direction collides.
• [x] (0, 1) chunk: Placed and removed chunks aren't rendered, but they do seem to have exterior collision in +/-x and +z faces.
• [ ] (1, 0) chunk: Rendered and have exterior collision on three sides: +/-z and +x.
• [ ] (0, -1) chunk: Rendered and has exterior collision on only -x.

[bbarker]

Have now addressed some of the collision issues in b743a5ada01d501729b76e4bf26b5194279b2cad due to unnecessary >0, <=16 checks, but more subtle issues remain. Need to compare position of placed block and detected block collision to debug, starting in (-1,0) chunk.

[bbarker]

Modified list (note: not testing the bottom (-y face) in this list):

• [ ] Removed chunks are (typically) not rendered outside of the origin chunks, and removed chunks in the origin may not be rendered after having visited a different chunk.
• [ ] (-1, 0) chunk: only the outer face in the -x direction collides. The z faces and the upper face are shifted in the -x direction by 1 block. Removing the expressions - (if (chunk.xx < 0) 1 else 0 for the tentativeBlock selection do not alter this effect, so it is likely still an issue with the collision code.
• [ ] (0, 1) chunk: Placed and removed chunks aren't rendered, but they do seem to have exterior collision in all faces now.
• [x] (1, 0) chunk: Rendered (even removed are rendered) and have exterior collision on all faces, but top face (+y) seems to be slightly off - sometimes possible to fall through.
• [ ] (0, -1) chunk: This one is hard to test now, but seems to not be rendered any longer and seems to only have faces in +/-z faces.

[bbarker]

It appears we may need Math.round instead of toInt for negative chunks; limited use in 995704c6654a19de8e64123b171cbe0eae012503 seems to confirm this, need to investigate more.

Update: the rounding fixes have largely helped but not all is perfect in 0947544c67ec4e66d1c26397131a49397e3bc6ab, need to get some rendering issues for non-origin chunks resolved to make debugging collision detection easier.

[bbarker]

Merged progress so far to master in 9ec1b76a53fb9ee00d711f80bdad467e00d62ddc.

There are a number of rendering issues, including this one, that would be easier if controls were improved (#3).