New function `configuration-layer/layer-declaredp`
Move window-numbering package config into its own init function
Neotree window number is now always 0

This other windows keep their number
Add a feature to toggle transparency

This sets the initial `alpha` frame parameter so that transparency could
be toggled later on. The level of opacity can be configured from a
user's .spacemacs through the variables `spacemacs-active-transparency`
and `spacemacs-inactive-transparency`.
Updated install section of haskell readme
set haskell-process-type to auto

Should work in more use-cases
Removed ghci-completion package

- ghci-completion is redundant when using flycheck-haskell
Merge remote-tracking branch 'refs/remotes/upstream/develop'
Add ~/.cabal/bin and ~/bin to path for haskell compat