use this enum for some function arguments and struct members .
drop some include "variable.h" which are no longer needed ,
propably many more could be droped .
drop #define VT_* which have been used as workaround for the type mess .
* frontend/breakp2.c, frontend/newcoms.c, frontend/postcoms.c,
frontend/resource.c, frontend/terminal.h, frontend/variable.c,
frontend/variable.h, frontend/com_compose.c,
frontend/com_display.c, frontend/com_setscale.c,
frontend/com_strcmp.c: Include files update.
* parser/var2.c, parser/var2.h: Empty files, removed.
* parser/Makefile.am: Updates for removed files.
* parser/lexical.c: Small adjustments
* parser/input.c, parser/input.h: Input, output and error streams
handled in the frontend. Moved to the frontend directory.
* frontend/streams.c: Its new home.