Field.Pretty improvements

As small change, there's a empty line after multiline fields
in a pretty output.

Add freeTextField

First step towards
https://github.com/haskell/cabal/issues/5971

Fix #5967; Also make Show Verbosity print everything

Fix comment to avoid haddock parsing error

Fixes #5747

[ci skip]

Signed-off-by: Nikolai Obedin <dev@nkly.me>

Fix some typos [ci skip]

Minor fixes

Don't pass --{disable,enable}-executable-profiling to lib:Cabal-1.22.0

In Cabal-1.22.0 this flag was temporarily removed, but it was added back
in Cabal-1.22.1.0.

Resolves #5946

Include the domain name in the password prompt

Fix some markdown in the local builds docs

Tidy up AppVeyor slightly

it turns out that Cabal will happily send your password to whatever the
last configured `repository` is (see #4402). This is a security risk!
Therefore, following common best practice, this patch makes sure to
include the domain name in the username and password prompts.

[ci skip]

Add bkpcabal01 regression test-case and fix the bug

[ci skip]

The new `cabal-head` packages now automatically detect AppVeyor and set the required paths. (You can see this in the build log)
also use AppVeyor time better by not building branches to open PRs since the PR itself is also built.

Also tweaks testcase's .cabal metadata

Alas, we can't deduplicate the code because the fine structure is
a bit different, but it's basically the same fix as in the Cabal case.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

bindir-method/install-method, installdir, new-install flags in SavedConfig -- 3.0 version