quant: scale psy-rdoq by lambda

Using L1 lambda in RDO is unorthodox, but we already do the same thing with
psy-rd energy and it seems to work decently well here weighting the
reconstructed DCT coeff against the RD cost in psy-rdoq.

The goal is for psy-rdoq 1 to be a safe and sane default

--HG--
extra : amend_source : f34c151c548293215b77a339cf0e4701877c47ba
rdcost: add arbitray scale to make --psy-rd 0..2 range give acceptable quality

--HG--
extra : amend_source : b527eb0999048c8021fe2640cc98adcc6e2298c6
param: re-enable psy-rdoq range check for [0..10], print with two digits

--HG--
extra : amend_source : 1bd0d7338a1a8d4aa4b55357a374fa18d3edbc4f
quant: set lambdas at the same time quant QP is configured
analysis: nits
rest: improve documentation for psycho-visual options

--HG--
extra : rebase_source : ab42f8b75dbb561994ce660aba3adbaf61203337
slicetype: use fast intra scan unconditionally in lookahead

We don't want the lookahead output to be variable depending on --fast-intra
since this would make two-pass turbo mode more difficult.
param: enable --fast-intra for all fast modes and turbo first-pass, document