simplify loop in tresize

Signed-off-by: Roberto E. Vargas Caballero <k0ga@shike2.com>
reset the alt screen in treset

Signed-off-by: Roberto E. Vargas Caballero <k0ga@shike2.com>
Make useful DEL in application mode

DEL key has to generate the sequence ^[P in application mode,
because such sequence means delete current character. It implies
that the character sent in keypad mode must be ^? (DEL character).
Fix definition of CONTROLC0

DEL character is not thecnically talking a C0 control character,
although it has some common properties with them, so it is useful
for us consider it as C0. Before this patch DEL (\177), was not
ignored as it ought to be.
Improve execsh() and don't allow anonymous shells

This patch improves the shell selection on execsh and forbid
shell with users don't registered in the passwd file.
added .gitignore file
symlinked config.def.h to config.h
initial commit of my config.def.h
default font is now DejaVu Sans Mono for Powerline