Taking over maintainership of cpphs, HaXml, hscolour, and polyparse

[Peter Simons]

Fellow Haskell Hackers,

it appears that Malcolm Wallace has lost interest in maintaining his
packages on Hackage. Some of them are rather important dependencies for
others, and therefore I'd like to take over maintenance of the following
libraries:

 - cpphs
 - HaXml
 - hscolour
 - polyparse

Polyparse, in particular, needs a maintenance update to fix build issues
with GHC 8.6.1. The absence of a working release blocks packages like
hlint from supporting that compiler [1].

I tried to contact Malcolm on 2018-09-24 via e-mail. Others have also
tried to reach him through WhatsApp other channels. Unfortunately,
no-one has received a response, which is why we decided to go through
with this process.

Best regards,
Peter


[1] https://github.com/haskell-infra/hackage-trustees/issues/186