Miscellaneous transmission mode selector enhancements

[unorthodox-paradox]

• [x] Pushed transmission mode selectors shall blink when the update request cannot be satisfied, either because of the engine being off, or the gearbox malfunctioning. Blinking frequency shall be slower in the former case than in the latter. Note that the case where transmission mode update cannot be carried out due to other constraints (e.g. R pushed while moving forwards) will be disregarded for now, due to lack of a normative specification. Also make blinking and intervals configurable via .cti-vars.
• [x] Have the additional constrained (see #75) selectors share the same default and light-map texture. They currently use 3x2 distinct textures for no good reason.
• [x] Add .cti-var for configuring whether the N selector is to remain engaged (pushed) when no longer triggered (ZF selector panels), or reset back to its original position (Voith panels).
• [x] Add .cti-var for configuring whether, when specifically both at standstill and the effective transmission mode is neutral, acknowledgement of selection of any mode besides N requires the user to hold down the brake pedal or not.
• [x] Cockpit-wise, when already moving or standing still in an effective mode other than neutral, acknowledgement is unconditionally independent of the brake pedal's angle.
• [x] VDV shall report "gear engaged" for reverse transmission mode being effective as well, in addition to the forward-driving modes, when engine ignition is attempted.

[unorthodox-paradox]

The soon-to-be-committed finishing touches to 1.5.3 will introduce following changes:

• Transmission mode transitions and constraints have been re-implemented as part of the transmission (ZF Ecomat 2/4 & Ecolife) script. The cockpit now solely addresses transmission mode selector triggering and illumination.
• Transmission mode selector blinking has been extended to cover a range of "dashboard-from-gearbox-mode-desync" cases:
  • When the engine is not running, and any mode besides 'N' is effective.
  • When, irrespective of engine state, at standstill and without braking (depending on antrieb_cfg_xxx_standstill_non_neutral_transmission_mode_update_requires_braking), an update from 'N' to any other mode is requested.
  • When moving forward too fast, an update from 'N' to 'R' is requested.
  • When moving forward too fast, an update to a constrained mode ('1'/'2'/'3') is requested.
  • When, while in a constrained mode, the gearbox preemtively upshifts to prevent damage, due to the velocity having exceeded a limit considered safe for the maximally attainable speed of the effective mode.
• In the blinking-on-malfunction case, cp_cfg_xxx_transmission_mode_selector_blinking_mode_malfunction allows one to configure whether:
  • 0: The selector corresponding to the transmission mode currently effective shall remain constantly on.
  • 1: The selector of the mode currently effective shall blink.
  • 2: The selectors of all modes shall blink synchronously.
  • 3: The selectors of all modes shall blink sequentially ('1', then '2', ..., then 'R').
• In the blinking-on-desync case, transmission_mode_selector_blinking_mode_desync allows one to configure whether:
  • 0: The selector corresponding to the transmission mode currently effective shall remain constantly on.
  • 1: The selector of the mode currently requested (pushed) shall blink.
  • 2: The above cases combined: The selector of the effective mode shall remain constantly on, while the selector of the requested mode shall blink.