This PR moves the public API headers into a top-level include directory. This makes it easier to find the public API of cvc5 and makes the install headers script obsolete.
Fixes#9553Fixes#9556
This updates our string reductions for `to_lower`, `to_upper`, `from_int`, `to_int` to use STRING_NTH instead of STRING_TO_CODE applied to STRING_SUBSTR.
It optionally replaces STRING_TO_CODE with STRING_NTH during preprocessing (true by default).
This is work towards efficient support for `to_lower`/`to_upper`.
The public cvc5 API now lives in the cvc5 namespace. All internal parts were moved into the (new) internal namespace.
The final hierarchy will be as follows:
cvc5
~~ public API
::context
::internal
::parser
::main
After this PR it will be:
cvc5
~~ public API
::internal
::context
::main
::parser
