Added trace-define, trace-let, trace-lambda

In racket/collects/racket/trace.rkt
Including build status and docs on pkgs.
Fix some typos
fixed error message according to Oliver Flatt's suggestion; Rackety
fixed error message according to Oliver Flatt's suggestion, take 2
Merge clauses even when no clause is consistent with the expected type.

Closes PR14731.
Fix type queries.
Fix the fix to type queries.

Should have been included in the original commit.
fix color-frame docs

closes PR 14733
make some arity error messages for ->i contracted functions
slightly less terrible

... but ->i still doesn't do as good a job as -> and ->* do for arity
errors (specifically, ->i is still letting the blame-less errors that
application constructs thru when it could be assigning blame)
Fix contract.
Include syntax/parse in defmacro.scrbl

So that can be hyperlinked
Fix more doc links.
pict: make `hc-append`, etc., match the docs

Allow pict arguments, with or without a separation-size
argument.

The recently added contract has rules out providing a
separation size with no arguments, which had been allowed
before. The underlying problem, though, was an inconsistency
in the implementation that allowed 0 pict arguments only
in the case that a separation size is provided.
restore accidentally removed GC check

Fixes a mistake in commit 768b93be82, which dropped a check that is
needed to trigger GCs during a sequence of large-block allocations.

Closes PR 14738