[PATCH 0/6] MR5794: Cmd engine rewrite (part V)

[eric pouech (＠epo)]

The aim of this serie is to split FOR loop instruction parsing from
it's execution.

In more details:
- introduces CMD_FOR_CONTROL structure to hold parsed FOR instruction
- improves the support of FOR loop variables (%0-%9 are now available)
- fixes a couple of issues in FOR instruction parsing (missing \t detection
  in a couple of places, quotes management),
- fixes a couple of issues in FOR execution (mainly missing delayed
  substitution of some constructs)
- code refactoring with helpers