Allow generation of Eclipse and IntelliJ project files
Removed nonConditionalRule as this was updating a "var".
This rule which identifies an optional "column prefix" has been extracted into its own function "explicitColumnPrefix" which can now be used by any other "rule" functions; currently only "is" rule.
"column prefix" rule uses the parser combinator "into" to allow its extracted text to be captured and passed on.
Removed conditionalRule as this was only introduced because of "nonConditionalRule I guess.

Rule no longer has "explicitColumn" as a var but it now given to primary constructor as an "implicit".
IsRule again the only rule currently using "explicitColumn" has also been given this implicit.