visibility of the cursor is not saved/loaded anymore.
scrolling up/down is fixed.
added RI and RIS sequences.
fixed cursor drawing bug.

cursor keys are handled in kpress according to the Application Mode (DECPAM).
define & enum were renamed.
tcursor() is now tmovecursor() which is more correct.
tcpos() is now tcursor(), as DECSC is also supposed to save attributes.
capnames are indicated whenever possible.

Currently:
alsamixer looks fine, totally usable.
ncmpc is almost ok.
emacs looks like shit.

Due to consideration of POSIX compliance issues config.mk had
to be removed. Configuration variables can be overridden by
environment variables or specified via command line.

Additionally all pretty-printed messages were removed and
built-in rules are used. This also simplifies and purges
the Makefile.

Ptm and pts are used by pty.c, thus they have to be non-static.