Merge branch 'feature/blanchard/builtin-to-instantiate' into 'master'

headers/header_spec.txt

src/plugins/builtin/tests/options/test_config

src/plugins/builtin/tests/stdlib/test_config

src/plugins/builtin/tests/string/test_config

src/plugins/instantiate/.gitignore

src/plugins/instantiate/Instantiate.mli

src/plugins/instantiate/Makefile.in

src/plugins/instantiate/README.md

src/plugins/instantiate/basic_blocks.ml

src/plugins/instantiate/basic_blocks.mli

src/plugins/instantiate/configure.ac

src/plugins/instantiate/instantiator_builder.ml

src/plugins/instantiate/instantiator_builder.mli

src/plugins/instantiate/options.ml

src/plugins/instantiate/options.mli

src/plugins/instantiate/register.ml

src/plugins/instantiate/stdlib/basic_alloc.ml

src/plugins/instantiate/stdlib/basic_alloc.mli

src/plugins/instantiate/stdlib/calloc.ml

src/plugins/instantiate/stdlib/calloc.mli