installation of kdu_expand requires manual setup of library variable

[jonatansve]

When running kdu_expand the first time it gives an error that the file cannot find libkdu_v72r.so

Suggested fixes:

1. Write the import in the code:

LD_LIBRARY_PATH=$LD_LIBRARY_PATH:~/$kakadu.bin... or similar
export LD_LIBRARY_PATH

2. Or just add the above to documentation for the user to add manually

What do you think Jan?