Reconnection, array support and fixes

Merged pull request #1

Changes

• refactor main to use async functions
• refactor notification handler
• refactor findTag
  -- fixes where potentially findTag resolves wrong tag eg. prog.tag vs prog.tag1
  -- fixes where read/write for array/structures size and offset resolved correctly to subtag not whole structure / array
  -- implemented array index (eg. program.array[1].structure is now resolved correctly)
• refactor parser, structure parser, array parser
• implemented eslint / prettier
• implemented better error handle, we could end end up with "promise unhandled rejection" in some cases
• implemented reconnection & moved connection to separate Class
• implemented Array write
• implemented notification handle resubscribe after reconnection
• fixes dependency cycle
• fixes param reassign
• fixes invokeId may end up ERR_OUT_OF_RANGE err
• fixes where sync functions like parse and encode use async this.getDataTypes without await

Breaking changes

• subscribe / unsubscribe are not public methods anymore
• Arrays are returned as Arrays not as object
• since Client is instance of EventEmitter, then 'error' event should be listened, otherwise you might get Unhandled 'error' event if connection failures for example