More elucidating messages after typos in command line arguments

[bestchai]

Running Texada with config file containing

#!c++

-m -f 'G((("scope_p" & p) & ("scope_q" & q) ) -> ((("scope_r" & r)-> ("scope_s" -> s)) W (("scope_p" & p) & ("scope_q" & !q)))) & F((("scope_p" & p) &  ("scope_q" & q))& !((("scope_p" & p) &  ("scope_q" & q))->(("scope_r"->!r) W (("scope_p" & p) &  ("scope_q" & !q)))))' scope-semantics --parse-mult-prop

(and a trace at the end) gives a segfault and no other messages. Valgrind indicates it is a stack overflow. Might be good to find a way to have some more elucidating messages here. Probably texada tries to open the argument with no -- as the file and finds an empty file and does something weird. Might be good to warn the user about there being an empty file.

[Issue created by carolemieux: 2016-04-27]