travel: regexp constant renamed

Signed-off-by: Adrian Matejov <a.matejov@centrum.sk>
travel: examples are now grammatically correct

Signed-off-by: Adrian Matejov <a.matejov@centrum.sk>
travel: more readable "zajtra" and "pozajtra" code

Signed-off-by: Adrian Matejov <a.matejov@centrum.sk>