Emit warnings for typos or mistakes in labels and rules

There are no warnings for certain mistakes made in the labels and rules file, which stop processing in IRIS. The following mistakes are currently not picked up by python:

- labels:
* type is missing, e.g. ;1,30,64;NLHoliday;holidays;0;;
* type is incorrect, e.g. ;1,40;NLWatWie;typeAmbiguous: words 'wat', 'wie', 'hetgeen';0;; -> ":" instead of ";" as separator
* superfluous space after label line (error message in IRIS: 'Invalid attribute name')

- rules:
* empty field, e.g. 1980;30;NLOndvw:"dat"|\*NLArt:NLAttradj:NLCon:NLPrep|NLNumber:NLQuantity:NLOrdnum|NLTimeconcept|\*typeConcept|NLVerb;\*|\*|NLAdvTime|+Join|\*|\*|; -> nothing follows last '|'
* superfluous quotation mark, e.g. 1207;40;SBegin:NLAndOrBut|NLDat"+^NLOndvw|NLCon:NLRelCon|NLVerb;\*|NLArt|NLCon|\*; -> quotation mark after 'NLDat'