experimental support for multiple windows (fixes #212, fixes #170)

app/lib/lru.ts

@@ -0,0 +1,15 @@
+let lru = require('lru-cache')({ max: 256, maxAge: 250 })
+
+let fs = require('fs')
+let origLstat = fs.realpathSync.bind(fs)
+
+// NB: The biggest offender of thrashing realpathSync is the node module system
+// itself, which we can't get into via any sane means.
+require('fs').realpathSync = function (p) {
+    let r = lru.get(p)
+    if (r) return r
+
+    r = origLstat(p)
+    lru.set(p, r)
+    return r
+}