Simplify trade input data format

[trevorb1]

In the datasoureces/Trade.csv file, we input the technology and commodity names manually following this convention...

This seems like we are cruising towards a clerical error if we are ever wanting to update/modify it, as it is easy to accidentally mistype a technology or commodity name. It would be nice if we just input the regions and fuels, then the code takes care of the rest. Something like....

Region 1	Region 2	Fuel	Import Eff. (%)	Export Eff. (%)
CANWS	CANMW	ELC	95	95
CANWS	USANW	ELC	90	95

The specifics of what the table actually looks like probably needs a little more thought. Just thinking it might be easier to read (and less prone to errors) if we let the code do more of the tech/fuel name assembling