Synch German string constants with latest.
repair for picture-to-bitmap conversion
fix define-judgment docs

change so mode-spec is not optional in grammar
make `list-ref' future-safe even for large fixnum indices
make `make-fsemaphore' atomic (i.e., not blocking)
Fix typesetting of `code:blank` in the Scribble docs
fix docs for define-judgment

clarify the places where unquotes are not allowed
added checksum calculation
Move `define/match` to `racket/match`
More float conversion optimizations.
Generate ->* contracts for functions with both optional and keyword arguments.
Make expt type more correct.

Closes PR13170.
Add type for raise-argument-error in TR.

Closes PR13132.
More types for raise-* functions.
Added working for/vector:, for*/vector:, for/flvector:, for*/flvector:

Closes PR13185.
Added plet:
Document plet:.
Added typed/untyped-utils (just require/untyped-contract for now)
Add test.
Added examples to string-ports document

In cooperation with Xiangqi Li and Kevin Tew