Fix documentation of spawn
Merge pull request #47 from imzyxwvu/master

Some fixes to improve compliance.
Add explicit Apache license
Merge pull request #51 from luvit/license

Add explicit Apache license
Merge pull request #42 from hnakamur/fix_spawn_doc

Fix documentation of spawn
Organize src folder.

Now we only export luaopen_luv.  This should reduce the area of conflict
when importing into luvit eventually.

The source files are now broken up by responsibility, but all act as a
single file thanks to C includes

There are now Makefiles for lua, luajit and luvit.
Merge pull request #53 from luvit/combine

Merge source files into one.
+= instead of = for CFLAGS and LDFLAGS
Merge pull request #1 from luvit/master

Head to the official version.