Allow passing a callback to the chained init on instantiation
Proxy native response object - immutables are cached and loop is run
Remove unneeded passthrough - it's the fs stream which must be 'finish'ed
WebResponse: data can be empty without error. Throw a custom one.
Remove whitespace
Do not update uri on Change finished
Document is able to load only when Change event finished is received.
Prevent navigation only when not loading
After unload, some events can be dropped
Fix unload/load logic so it can be chained
Throw error when calling response.data without callback
Fix all tests
Split chained pdf/html calls from internal ones
Split chained png from internal call too