Added README.md for world package.

This README will help me develop and maintain the world package,
hopefully.
Added README.md for world package.

This README will help me develop and maintain the world package,
hopefully.
Merge branch 'world-package' of github.com:mathuin/terroir into world-package
First pass at level.dat creation.

The level.dat works in the game and passes the tests.
Updated docs and code to use new level features.

The documentation now contains references to level files.  The world
package now uses the level file generator to build very spare worlds
that actually work in the game.  All tests pass, coverage is better
than I expected.
Refactored level-writing code.

Subject says it all!  Still passing tests.
First pass at chunks and regions.

Used README.md information to create structs for chunks and regions.
Removed superfluous comment from world.go.
More work on the chunk code, including some tests!

Coverage percentage is dropping.  First rough chunk tag writing done.
New NBT utility functions aid in building worlds.

Lots of compound tag construction, so I refactored the code and put it
in the NBT package.
Refactored chunk and level code.

Broke down Half and Double functions into simpler more testable components.

Used new NBT functions in chunk and section construction.

Made a note to remind myself to fix the level tests to use maps.
Moved utility funcs and tests, and more.

Also refactored level tests to use requiredTags approach and made
progress towards testing chunks and sections.
Changed chunk and utils functions to be more generic.

Also added more accessors for chunks and sections.  Still better than
half code coverage with testing, but should improve soon.
Minor changes to NBT package plus debugging.

Turns out TAG_List's can have nil payloads -- who knew?  Minor cleanup
in readCompound() makes me think I'll have to do some more cosmetic
changes.  ReadTag() also now reports an error if no PReader is found.
Refactored world code to match requirements.  It works!

With a driver program, I was able to read an entire region file.  I
need to finish importing components of the driver program into the
readRegion function, but I wanted to check this in first.
Added initial support for entities and points.

In order to faithfully read and write worlds, I will need at least
some support for entities and such.  This is enough to get by for now.
There's also some support for points added, including tests.
Refactored WriteTag method.

It's actually a method, not a function, so I fixed it.
Cleaned up code and made it easier to understand.

Subject says it all.
Stash juggling, part one.

First attempts at reading worlds and region files involved stashing a
lot of code.  I need to commit what I have and then play with the stash.
Region files can now be read and written!

I was able to read a region file, make changes, and write it back, and
it worked.  Tests also pass.  They need to be beefed up severely, of
course.  The driver code needs to be migrated into the repository as
well.
First pass at world-reading driver.

Need to write a corresponding writer for worlds, then I can start
moving functionality from chunks and sections up to the world level as
appropriate.