More fixes for tabs, and added Magnus Karlsson's Pipistrello (Xilinx) port.

Hi Rick, can you merge this into your tree?

The changes are piling up:
- Your added PDF's were merged
- More tab->space conversions
- Added Magnus Karlsson's port to Pipistrello (Xilinx Spartan-6) (*)
- Added Andy Silverman's port to Digilent Nexys4 (Xilinx Artix-7) (*)
- Fixed bug in cog_ctr.v that Andy found today (http://forums.parallax.com/showthread.php/157387)

(*) There are some minor details about Magnus and Andy's directories that I don't agree with, but I'll work those out later when I have more hard disk space to install the Xilinx tools.

After you merge this, you should post a pull request to Heater (@Zicog) and he should stage a release because of the bug fix. It's a minor bug but it probably breaks all timer functions except the ones that use the PLL.

Thanks!

===Jac