🔧 a little configuration and an update to zarro

reconfiguring for newly-supported zarro syntax makes the package.json easier to read (:

.zarro-defaults

@@ -0,0 +1,17 @@
+# zarro defaults file:
+# place one VARIABLE=VALUE per line below
+# variables here will not override existing environment variables
+#   unless prepended with a bang, ie
+#     !VARIABLE=Value
+#   so this means anything you set in your package.json, eg with
+#   cross-env, will override what's in here unless you've specifically
+#   marked the setting in here as forced with !
+
+# instruct nunit console runner to run in a single process
+NUNIT_PROCESS=Single
+
+# determines how many tests can run in parallel - 1 is fine
+MAX_CONCURRENCY=1
+
+# specify what to build (prevents accidental build of any other sln)
+BUILD_INCLUDE=src/log4net.sln