Remove ".sh" from file names.

Refactor so it does not rely on PWD being the repo basedir.
Fix assumptions about HG and GIT use.

bin/blackbox_edit_start

@@ -0,0 +1,26 @@
+#!/bin/bash
+
+#
+# blackbox_edit_start.sh -- Decrypt a file for editing.
+#
+
+. _blackbox_common.sh
+
+for param in """$@""" ; do
+  unencrypted_file=$(get_unencrypted_filename "$param")
+  encrypted_file=$(get_encrypted_filename "$param")
+  echo ========== PLAINFILE "$unencrypted_file"
+
+  fail_if_not_on_cryptlist "$unencrypted_file"
+  fail_if_not_exists "$encrypted_file" "This should not happen."
+  if [[ ! -s "$unencrypted_file" ]]; then
+    rm -f "$unencrypted_file"
+  fi
+  if [[ -f "$unencrypted_file" ]]; then
+    echo SKIPPING: "$1" "Will not overwrite non-empty files."
+    continue
+  fi
+
+  prepare_keychain
+  decrypt_file "$encrypted_file" "$unencrypted_file"
+done