Flatten src directory

* Move src/app to src/
  * Move src/stdlib to src/
  * Remove src/app and src/stdlib from NODE_PATH

src/keystroke-pattern.pegjs

@@ -0,0 +1,3 @@
+keystrokePattern = key:key additionalKeys:additionalKey* { return [key].concat(additionalKeys); }
+additionalKey = '-' key:key { return key; }
+key = '-' / chars:[^-]+ { return chars.join('') }