wasm: parse: Fix parsing of br_on_cast and br_on_cast_fail

See merge request !302

Add issue-deprecation-warning

See merge request !299

* lib/guile.scm (issue-deprecation-warning): New symbol.

Add const

See merge request !300

* lib/guile.scm (const): New symbol.

Add &external-error exception type

See merge request !298

ci: Use large instances for jobs that run the test suite.

See merge request !297

Adds filter-map and find to srfi-1 stubb module

Closes #346

See merge request !296

ffi: Replace missing import %error with syntax-violation

Closes #345

See merge request !294

Fixes #345.

Fix cond-expand in define-library forms

See merge request !292

Make stack capturing and backtrace printing API public

See merge request !291

Add more string utilities

See merge request !285

* lib/guile.scm (string-reverse): New symbol.

* lib/guile.scm (substring): Wrap to support optional end arg.

* lib/guile.scm (string-trim, string-trim-both, string-trim-right): New symbols.
* test/test-strings.scm: Add tests for string-trim et al.

* lib/guile.scm (%string-trim, string-split): Use char-sets for char-pred.
* test/test-string.scm: Add string-index test using char-sets.

* lib/guile.scm (string-rindex): New symbol.
* test/test-strings.scm: Test string-rindex.

I copy/pasted some stuff from the SRFI-14 reference implementation and
some tabs snuck in.  Thanks to Juli for pointing this out.

Add a few basic character sets

See merge request !290

Limited to ASCII range for now.

Replace define-inlinable stub with real implementation

See merge request !289

Add partial implementation of 'while'.

See merge request !288

Switch eval to use modules as representation of environments

See merge request !287

This is good enough for Goblins' existing usage of 'while', but it
lacks 'break' and 'continue' support.

Add run-time representation of modules

See merge request !286

This will replace eval environments

The parent fields are implicitly part of the constructor.

Bits and pieces needed for (web uri) support

See merge request !284