flake: Introduce PyThermostat scripts to devShell

Make executable Python scripts in the PyThermostat root available in the
development shell (e.g. thermostat_plot, thermostat_autotune,
thermostat_test).

flake.nix

@@ -63,12 +63,24 @@
         version = "0.0.0";
         src = "${self}/pythermostat";
 
-        propagatedBuildInputs =
+        propagatedBuildInputs = with pkgs.python3Packages; [
-          with pkgs.python3Packages; [
           numpy
           matplotlib
         ];
       };
+
+      pythermostat-dev-wrappers = pkgs.runCommandNoCC "pythermostat-dev-wrappers" { } ''
+        mkdir -p $out/bin
+        for program in ${self}/pythermostat/*.py; do
+          if [ -x $program ]; then
+            progname=`basename -s .py $program`
+            outname=$out/bin/thermostat_$progname
+            echo "#!${pkgs.bash}/bin/bash" >> $outname
+            echo "exec python -m $progname \"\$@\"" >> $outname
+            chmod 755 $outname
+          fi
+        done
+      '';
     in
     {
       packages.x86_64-linux = {
@@ -90,11 +102,15 @@
             openocd
             dfu-util
             rlwrap
+            pythermostat-dev-wrappers
           ]
           ++ (with python3Packages; [
             numpy
             matplotlib
           ]);
+        shellHook = ''
+          export PYTHONPATH=`git rev-parse --show-toplevel`/pythermostat:$PYTHONPATH
+        '';
       };
 
       formatter.x86_64-linux = nixpkgs.legacyPackages.x86_64-linux.nixfmt-rfc-style;