Refactoring datalog in common packages (#249)

* using datalog from common packages

* upgrading common package link

* updated block signatures

* more docs

libs/datalog/targetoverrides.ts

@@ -0,0 +1,57 @@
+namespace datalog.ev3 {
+    /**
+     * A datalog storage for the EV3
+     */
+    export class EV3DatalogStorage extends DatalogStorage { // implements DatalogStorage {
+        private _filename: string;
+        private _buffer: string;
+        private _storage: storage.Storage;
+
+        /**
+         * Creates a new storage for the datalog
+         * @param storage 
+         * @param filename 
+         */
+        constructor(storage: storage.Storage, filename: string) {
+            super();
+            this._filename = filename;
+            this._storage = storage;
+        }
+
+        /**
+         * Initializes the storage
+         */
+        init(): void {
+            this._storage.remove(this._filename);
+            this._buffer = "";
+        }
+        /**
+         * Appends the headers in datalog
+         */
+        appendHeaders(headers: string[]): void {
+            this._storage.appendCSVHeaders(this._filename, headers);
+        }
+        /**
+         * Appends a row of data
+         */
+        appendRow(values: number[]): void {
+            // commit row data
+            this._buffer += storage.toCSV(values, this._storage.csvSeparator);
+            // buffered writes
+            if (this._buffer.length > 1024)
+                this.flush();
+        }
+        /**
+         * Flushes any buffered data
+         */
+        flush(): void {
+            if (this._buffer) {
+                const b = this._buffer;
+                this._buffer = "";
+                this._storage.append(this._filename, b);
+            }    
+        }
+    }
+    // automatic hook up
+    datalog.setStorage(new datalog.ev3.EV3DatalogStorage(storage.temporary, "datalog.csv"));
+}