IRF igbt table: initial commit of the IRF download.

source:	http://ec.irf.com/v6/en/US/adirect/ir?cmd=eneNavigation&No=0&N=0+4294841625&numRecs=95
	clicked on the 'Download Spreadsheet' link
	and converted xls to fods.
IRF igbt table: Added information about transistors with diodes

source: http://ec.irf.com/v6/en/US/adirect/ir?cmd=eneNavigation&No=0&N=0+4294841624&numRecs=120
	clicked on the 'Download Spreadsheet' link
	removed columns to match the existing spreadsheet
	copied & pasted under existing data
IRF igbt table: removed slow transistors from the list.
IRF igbt table: converted numbers from strings to floats.

According to:
	http://www.ryananddebi.com/2009/11/29/remove-apostrophes-before-numbers-in-openoffice-calc/
IRF igbt table: added load data, calculations and ranking.