Improved Input Selection

[zeugmaster]

Improved selector should take into account or optimize:

• input fee
• keyset age and active state
• amount sort order and privacy (e.g. spend small amounts vs. spend large amounts first)
• linear time and space complexity

The selector should use as parameters a list of ProofRepresenting objects, a target amount and unit.
Return values should be a Result type with either the optimal selection of proofs, or a meaningful failure response differentiating between different failure reasons (e.g. unit mismatch, insufficient amounts (not) including fees, etc.). This could also be done via error types.