v0.15.1

This is a minor release which enables updating indexers (via registered indexer setters) and supports functions
with &str parameters (maps transparently to ImmutableString). WASM is also a tested target.

Version 0.15.1 released to crates.io

Bug fix

• let s="abc"; s[1].change_to('X'); now correctly sets the character 'X' into 's' yielding "aXc".

Breaking changes

• Callback closure passed to Engine::on_progress now takes &u64 instead of u64 to be consistent with other callback signatures.
• Engine::register_indexer is renamed to Engine::register_indexer_get.
• Module::set_indexer_fn is renamed to Module::set_indexer_get_fn.
• The tuple ParseError now exposes the internal fields and the ParseError::error_type and ParseError::position methods are removed. The first tuple field is the ParseErrorType and the second tuple field is the Position.
• Engine::call_fn_dynamic now takes any type that implements IntoIterator<Item = Dynamic>.

New features

• Indexers are now split into getters and setters (which now support updates). The API is split into Engine::register_indexer_get and Engine::register_indexer_set with Engine::register_indexer_get_set being a shorthand. Similarly, Module::set_indexer_get_fn and Module::set_indexer_set_fn are added.
• Engine:register_fn and Engine:register_result_fn accepts functions that take parameters of type &str (immutable string slice), which maps directly to ImmutableString. This is to avoid needing wrappers for functions taking string parameters.
• Set maximum limit on data sizes: Engine::set_max_string_size, Engine::set_max_array_size and Engine::set_max_map_size.
• Supports trailing commas on array literals, object map literals, function definitions and function calls.
• Enhances support for compiling to WASM.