fix testing height and width for integer
implement height and width fallback for non-tty

once the height and width test is resolved to actually test, we
notice that running `nosetests 2>&1 | less' & etc. will fail:
the ioctl for TIOCGWINSZ fails for non-ttys (such as used by travis CI).
So, we fall-through to the LINES, COLUMNS environment variables, with
default values of (24, 80). (24, 80) has been a fairly standard
screensize for IBM PC-DOS and Apple ][ (beginning with the 80-column
character card), and C128. It is also the default for xterm, and many
classic terminals (such as a vt220) or emulating terminals (such as
telix), or bulletin board servers (such as teleguard) where a 'status
line' is also present.  In reality, these screens are capable of *25*
lines, but the 25th line is reserved for the status line.

Irregardless, non-zero must be returned for 'height' and 'width'
properties, as a value of 0 may become a "divide by zero" error
for mathematical operations that make use of the terminal height or
width in scripts that the user may chose to pipe to 'less -r' or some
such. In these situations, even though a value is returned, operations
such as 'move(x, y)' would still become 'stripped' due to 'is_a_tty'
becoming False, so there is no actual harm in providing a terminal size
that is not legal.
turtles all the way down for NullCallableString()

allow term.color(5)('shmoo') to succeed for terminals where stream is
not a tty.
resolve any 'must call (at least) setupterm() first' errors

avoid calling tparm when self.does_styling is False, which resolves
issues with attempting to use things (such as nosetests progressive)
where the terminal is not a tty.

its also a "pokemon exception" and is emitted for a good reason, we
certainly should not be calling tparm without calling setupterm()
first !
only perform color lookup for colored terminals
Merge remote-tracking branch 'origin/bugfix-3' into bugfix-1
Revert "Merge remote-tracking branch 'origin/bugfix-3' into bugfix-1"

This reverts commit 6d8fe019be1e1c1bd1238980288e1451d99eba80, reversing
changes made to 4cff579fbf395e7cfe3d12cb1b5f53ca535d6673.
docfix: 25 x 80 -> 24 x 80
Remove fallback to 24x80, and fix docstring formatting.

There are some advantages to falling back to 24x80: for example, the ability to easily render output based on height and width when being piped through `less`. However, that's a backward incompatible change--we explicitly documented the None return values in earlier versions--so I don't want to make it lightly. Reverting it for now because I want to get the unquestionable parts of this merged in.
Update version history.
Fall back to env vars to find height and width. Make the height-and-width test run. Close #46.