def prepare_options(options)
      options = engine.config.to_hash.merge(options)
      options.keys.each { |k| options[k.to_s.gsub(/_([a-z])/) { $1.upcase }.to_sym] = options[k] }
      options.delete_if { |k, v| v.nil? }
    end
def prepare_options(options)
      options = engine.config.to_hash.merge(options)
      options.keys.each { |k| options[k.to_s.gsub(/_([a-z])/) { $1.upcase }.to_sym] = options[k] }
      options.delete_if { |k, v| v.nil? }
    end
Responds for preparing compilation options.

 The next steps are executed:
 - is merges options into the engine config
 - it camelizes and symbolizes every option key
 - it removes nil values from the options

 @param options [Hash]
 @return [Hash]