Make opt-parent shared across different uses.
Make require/typed check its input more thoroughly.

Closes PR 13962.
Remove lfilters and make true/false-filter have a - prefix.
Add opt-expr and define-literal-syntax-class in utils.
Add simpler way of logging optimizations
Cleanup apply.rkt
Cleanup dead-code.rkt
Error message typo.
Generics props.
Biding -> Binding.

Closes PR13992.
Add an example for #:defaults.
minor db doc improvements
updated example paths

Closes PR 13995.
updated command line in docs

Closes PR 13996.
This file is only needed for `file/gif`.
Use `case` instead of `cond`
add immutable hash constructors and selectors to #lang info
clean up string-constants expansion and add dynamic-string-constant[s]

This saves about 200 bytes per use of (string-constant ...) in the .zo file.

Also, it now only requires a single string-constants file in phase 1
(instead of all 13) so that should be a savings of memory and time
when compiling .zos, too.