implement environment (contains variables) and write the head of the new
variable-commands
revive the create variable commands and add special commands for list
informations about variables
define a new parameter type for variable and implements a
candidates-chooser for auto-completion
after each command special global variables will be created one holds
the return code an the other one holds the return value of the last
command action
variables can now transfer to command as parameter
implements auto completion for variables as parameter value
Merge pull request #33 from rainu/issue-28-variables

Issue 28 variables