Reorganize code and don't use require_relative in exec_annotation

[duboism]

The current organization of the code makes the code a bit hard to install because the main script (exec_annotation) use require_relative to find the lib/ directory (therefore the lib/ directory and exec_annotation must be in the same directory).

I don't know the conventions in the Ruby community but if I trust this book, the main script (exec_annotation) :

• should be in the bin/ directory
• could perform some magic (modification of $LOAD_PATH) to find the lib/ directory (I'm not really fond of this idea; I would rather rely on the RUBYLIB variable and modify LOAD_PATH if this fails)
• use require 'lib/kofam_scan' instead of require_relative 'lib/kofam_scan'

This would simplify installation in our environment for example and probably in most environments too.

[duboism]

Any thoughts ?