Add min frame to compress config/fix closing bug

[adam-fowler]

These two are combined as the test for the min frame to compress revealed the close issue

• Added new config value which defines the minimum size of frame before running compression, previously this was fixed to 16 bytes which is quite low.
• Fix close issue where a handler receives a close frame so exits and then sends the responding the close frame. Previously it would then wait for a response. Fixed this by changing the closed boolean into an enum that details the close state, this catches if we have received a close frame already