Implement DUK_OPT_NO_STRICT_DECL
Document DUK_OPT_NO_STRICT_DECL
Release note: DUK_OPT_NO_STRICT_DECL
Add DUK_OPT_NO_STRICT_DECL to makefile (commented)
Merge branch 'ignore-strict-decl-option'

Add DUK_OPT_NO_STRICT_DECL as an experimental feature option to disable
processing "use strict" directives which can be useful when working with
legacy code (for instance, code that has "use strict" declarations but
has only been executed with an engine without strict mode support).