Support for HID-based partial super-fast flashing (#523)

* fix bug

* Fixed an issue where the Game of Life menu item was not appearing (#497)

* Starting on dapjs flashing

* Adding dapjs

* Connected

* Flashing works

* Double buffer flashing

* Add SHA computation function

* Run SHA code

* Swap SHA for murmur+crc

* Switch to dual murmur3

* Partial flashing works

* Remove unused code

* Move flashing code to external/sha

* Fix whitespace

* Cleanup binary genration scripts

* Add docs for hid flashing

* bump pxt-core to 0.12.132,

external/sha/genapplet.js

@@ -0,0 +1,48 @@
+let fs = require("fs")
+let s = fs.readFileSync(process.argv[2], "utf8")
+let infun = false
+let words = []
+for (let l of s.split(/\n/)) {
+    let m = /^00000000 <(.*)>:/.exec(l)
+    if (m && m[1] == process.argv[3]) infun = true
+    if (/^Disassembly/.test(l)) infun = false
+    if (!infun) continue
+    m = /^\s*[0-9a-f]+:\s+([0-9a-f]+)( ([0-9a-f]{4}))?\s+/.exec(l)
+    if (m) {
+        let n = m[1]
+        words.push(n)
+        if (m[3])
+            words.push(m[3])
+        if (n.length == 4 || n.length == 8) {
+            // ok
+        } else {
+            throw new Error()
+        }
+    }
+}
+
+let ww = []
+let pref = ""
+for (let w of words) {
+    if (w.length == 8) {
+        if (pref) throw new Error()
+        ww.push("0x" + w)
+    } else {
+        if (pref) {
+            ww.push("0x" + w + pref)
+            pref = ""
+        } else {
+            pref = w
+        }
+    }
+}
+
+words = ww
+
+let r = ""
+for (let i = 0; i < words.length; i++) {
+    if (i % 6 == 0) r += "\n"
+    r += words[i] + ", "
+}
+
+console.log(r)