* Upgrades the nixpkgs pin to 21.11.
* Removes nix code, sources, and attributes related to haskell.nix and
the code under pkg/hs.
* Continuous integration no longer builds (or packages/releases)
urbit-king (haskell).
* To continue to developing any haskell code under pkg/hs it's left as
a user exercise uto install and configure GHC/Stack.
As a consequence running nix-shell should be considerably more
performant and requires downloading or building less dependencies.
This prevents an error where the python2 version of the SDK tries to
use the monotonic library which is unable to detect the host operating
system inside the sandbox - exploding in typical python fashion.
By using python3 it obviates the need for the monotonic dependency by
using the builtin time.monotonic call.
This also sets -l (lite boot) by default for boot-fake-ship to speed
up the initial pier creation used by pills/tests, and uses
urbit.meta.arguments by default for tests - seems a little less likely
to footgun.
This also removes nixcrpkgs and OSX cross compilation in favour of
compiling on the target. x86_64/musl targets are still supported
on Linux.
All sources are now managed via niv (see nix/sources.json) and Haskell
package sets are provided/organised via IOHK's haskell.nix.
Some effort has been made to expose similar top-level attributes for
development, but in some cases there have been changes. Please see
the comments in the top-level default.nix and ci.nix files for usage.
