Break up easyinstall.sh script into modules

[rdmark]

Break out logical chunks of the easyinstall.sh script into stand-alone modules. Modular scripts can be stored in the newly added shell_scripts subdir.

[rdmark]

The script is over 1600 lines long at present. It's hard to read and maintain.

[rdmark]

Closing for now. Might revisit after introducing binary packaging which would deprecate a big chunk of this script.