Load deconfliction

[G1OJS]

Restructuring to enable load segment deconfliction (ensure NEC doesn't silently overwrite loads). Store required loads in NECmodel as variables for later checking instead of just writing the LD card strings to LOADS.

[G1OJS]

"Store required loads in NECmodel as variables for later checking instead of just writing the LD card strings to LOADS." done in V3.0.0