Implemented support for `in` and `not in` operators.
Merge remote-tracking branch 'upstream/master' into containment

Conflicts:
	py/runtime.c
Merge remote-tracking branch 'upstream/master' into containment
Fixed the merge so it worked and compiled and stuff
Add combined image to GitHub front page README.md
added zip()
sorted
made DEBUG control CFLAGS in Makefiles oter than stm as well.
Cleaned up sorted() as per Damien's suggestions.
Made sorted() raise an exception instead of aborting when given no arguments; moved around some things in objfun.c as a consequence
Add "buffer management" and "shrink" API calls to vstr.

vstr is initially intended to deal with arbitrary-length strings. By
providing a bit lower-level API calls, it will be also useful to deal
with arbitrary-length I/O buffers (the difference from strings is that
buffers are filled from "outside", via I/O).

Another issue, especially aggravated by I/O buffer use, is alloc size
vs actual size length. If allocated 1Mb for buffer, but actually
read 1 byte, we don't want to keep rest of 1Mb be locked by this I/O
result, but rather return it to heap ASAP ("shrink" buffer before passing
it to qstr_from_str_take()).
Add generic impl of stream .readall() method. Use one for unix io.FileIO.
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master' into containment
Merge remote-tracking branch 'upstream/master' into builtins

Conflicts:
	py/builtin.c
	py/builtin.h
	py/runtime.c
Implemented int(str) in UNIX
support int(str, basbase)
Add objtuple.h to allow embedding of tuples inside other objects.

This is useful because tuple is closest analog of C static array.
Refactor exception objects to have better impl of Python-side interface.

This implements internal args tuple of arguments, while still keeping
object useful for reporting C-side errors.

Further elaboration is needed.
Implement "is" and "is not" operators.

So far, don't work for strings as expected.