Switch the license to be LGPLv2/later, with small parts still remaining as GPLv2/later, by agreement of major contributors

When not running in place, check if the assumed data path in
../share/APPNAME exists. If it doesn't exist, fall back to ../data
instead. This allows the program to run successfully from the checkout
directory even without the run-in-place flag active.

When not running in place, check if the assumed data path in
../share/APPNAME exists. If it doesn't exist, fall back to ../data
instead. This allows the program to run successfully from the checkout
directory even without the run-in-place flag active.

fixed data path in porting.cpp for normal linux builds to get data from /binary/dir/../share/APPNAME