Update gemspec summary
Rename Syntax::InvalidContextError to ContextError
Refactor Syntax
Merge Syntax.register_request_for_dynamic_analysis into instance method
Refactor dynamic analysis request management in Syntax
Move dynamic analysis request of Have to Mixin::HaveMatcher
Move dynamic analysis request of OperatorMatcher to Mixin::ShouldBase
Add Syntax.conversion_target_node? and .dynamic_analysis_target_node?
Check whether #stub is RSpec's one with static list when no runtime data

This fixes #33.