give Summary and improved lineplots

[pweigmann]

New function showInputSummary shows summary of input data and matching between config and scenario/reference data. Warns if variables don't match.

Validation input summary:
 - Rows Scenario Data:  1360611 
 - Rows Historical Data:  1360611 
 - Models:  1 
 - Scenarios:  6 
 - Regions:  13 
 - Variables (config):  14 
 - Variables (data):  1510 
 - Variables (hist):  1510 
 - \# of config vars in scen data:  14 
 - \# of config vars in hist data:  10

Improved line plot function handles single-period thresholds as well as mixed amounts of thresholds for one variable: