Implement the escape key in GUI console to reset the current line

Based on github suggestion:

https://github.com/franko/gsl-shell/issues/16
Merge pull request #18 from vection/master

Substituted [] access in loops with :get and :set
Fix problem with "use" function with coroutines

Reported by P. Kulchenko, github issue:

https://github.com/franko/gsl-shell/issues/17
Merge pull request #19 from vection/master

Changes in lua-gsl makefile because GSL include directory was not found ...