Patch for purs 0.14 and Halogen 6

[and-pete]

This PR patches the project to work with the 0.14.1 compiler and with Halogen 6, as discussed in #80.

Reproducing here:

• Bumping the package set in packages.dhall to be compatible with the 0.14.1 compiler
• Removing each 'Just' from each of the HE.onXXXXX event handlers
• Replacing the SProxy and F.FormProxy with the new Proxy (from Type.Proxy)
• Removal of HH.HTML surface type from H.Component signatures
• Each use of CA.prismaticCodec has an new extra 'name' field as its first parameter, which needs adding
• Replacing the one use of H.tell in Main with the new H.mkTell
• Patching Affjax's addition of a timeout field to its request type
• A replacement for busEventSource that based on halogen-subscriptions