add new parameter "lb_force_fallback" (default=0)
Normally, if a reader has fallback and fallback_percaid parameters setted, LoadBalancing chooses it as fallback or as not-fallback reader, after evaluating its stats.
Setting lb_force_fallback=1 on same reader, with one of above parameters, we force LB to set reader ALWAYS as fallaback, and without consider its stats (ignore fails).
This could be usefull for secure fallback readers, that we want use as latest secure chance of decoding. It is same behaviour with LB off (mode 0).
The fallbacks are choosen with this priority:
- readers with fallbacks paramters (fallback or fallback_percaid) and lb_force_fallback=1
- readers with fallbacks paramters (fallback or fallback_percaid) and lb_force_fallback=0, if not already used as best readers
- readers with best lb_value, if not already used as best readers