Clean-up - Hydraulic Leveller DSAs

John Friede of HWH submits the following:

Eliminate Section 6.13 - Leveling System Control Panel
Move section 6.13.2 - Leveling Control Command into section 6.14 Leveling System Controller.
Eliminate SPN 256 (Keypad) for DSA 81 (Leveling System Controller).

Justification:

This removes a conflict between the "Leveling System Control Panel" and the "Leveling System Controller". The conflict dates to the original specification but has only recently been noted. This proposal removes the conflict and simplifies the overall presentation.