Version 0.7.5

Fixes:

• fix utils/find_chez_scheme_dir.sh for Alpine linux
• fix a pair of bugged assertions that were triggered by valid code {echo $A=}
• fix support for Chez Scheme down to 9.5.8

Improvements:

• rename shell builtin "error" -> "test"
• add command line option --load-file FILE and support for loading compiled Scheme libraries *.so
• add functions (alist->eq-hashtable) (alist->eqv-hashtable) (alist->hashtable) (file-rename)
(in-bytevector) (in-bytespan) (in-chargbuffer) (in-charline) (in-charlines) (in-charspan)
(in-gbuffer) (in-hashtable) (in-list) (in-span) (in-string) (in-vector)
(in-fixnum-range) (in-flonum-range) (in-range) (on-list)
(sh-bool) (sh-run/string-split-after-nuls) (sh-version) (string-replace)
• add macros (for) (for*) (library-reexport) (shell-test)
• add Fedora Linux build instructions to README.md
• add "Troubleshooting" section to README.md
• add more examples to README.md