…s and python module
This reverts commit a5712e1.
Fixes #46. Tested it on xterm linux, urxvt linux and mintty cygwin.
'tb_blit' is now deprecated, of course it will stay there for backward compatibility.
b) make an API guaranty that the screen dimensions are "negative" (no need to say -1) if tb_init() has not been called or if tb_shutdown() has been called without a subsequent tb_init() (i.e., if we're in tb screen mode). c) in tb_shutdown(), set termw/termh back to -1.
That will make negative numbers very large and discard them as a result.