Clean up distributed license files

[ibuclaw]

Noticed that the gpl.txt and artistic.txt files were still being distributed long after the switch to boost.

There are some remaining files that are still dual gpl/artistic licensed, so the first commit is re-licensing them as boost - so only @WalterBright or the original authors (@rainers @dheld) can sign these off.

The second commit is removing the gpl.txt and artistic.txt licenses, updating the readme.txt, and adding a new boostlicense.txt file which is included in the install-copy make rule, which I assume is used for creating release tarballs/zips.

[WalterBright]

I'm good with this.

[ibuclaw]

Did a copy-pasto error here.

[yebblies]

You could just get rid of UTFTest.cpp, it isn't compiled or maintained and isn't converted to D.

[ibuclaw]

You could just get rid of UTFTest.cpp, it isn't compiled or maintained and isn't converted to D.

That would be a separate PR. :)

[rainers]

Being mentioned as author of ldfpu.asm, I'm fine with relicensing it under boost.

[ibuclaw]

@yebblies - PR raised.

[dheld]

I approve.

[WalterBright]

Thanks, @rainers and @dheld

@ibuclaw fix the merge conflicts, and I'll pull it.

[ibuclaw]

Fixed conflicts.

[yebblies]

Auto-merge toggled on