Decompress puts file in wrong place

Would be very helpful if we could specify the output path for a `woff2_decompress` call. Right now, I need to run the call as follows:

cd /home/ubuntu/webfont-generator/vendor/woff2
./woff2_decompress /var/www/website.com/font.woff2

This then puts the font in the following location:

/var/www/website.ttf

This is presumably because of line #33 in `/vendor/woff2/src/woff2_decompress.cc`

string outfilename = filename.substr(0, filename.find_last_of(".")) + ".ttf";

Being able to specify the output location would address this, or else, have line #33 be smarter and store the decompressed font in the same directory from which it came.