fix prebuild, setting sketch, language ext issue (#557)

Author: Sneezry

package.json

@@ -2,7 +2,7 @@
   "name": "vscode-arduino",
   "displayName": "Arduino",
   "description": "Arduino for Visual Studio Code",
-  "version": "0.2.15-rc",
+  "version": "0.2.15-rc2",
   "publisher": "vsciot-vscode",
   "aiKey": "83dd2c27-6594-41d3-85a9-bdb22070eb42",
   "preview": true,
@@ -471,8 +471,9 @@
         "mimetypes": [
           "text/x-code-output"
         ]
-      }, {
-        "id": "arduino",
+      },
+      {
+        "id": "cpp",
         "extensions": [
           ".ino"
         ],

src/deviceContext.ts

@@ -249,7 +249,7 @@ export class DeviceContext implements IDeviceContext, vscode.Disposable {
     }
 
     public get prebuild() {
-        return this._prebuild.trim();
+        return this._prebuild.trim ? this._prebuild.trim() : "";
     }
 
     public get output() {

src/extension.ts

@@ -177,7 +177,7 @@ export async function activate(context: vscode.ExtensionContext) {
         const newSketchFileName = await vscode.window.showInputBox({
             placeHolder: sketchFileName,
             validateInput: (value) => {
-                if (value && /^\w+\.((ino)|(cpp)|c)$/.test(value.trim())) {
+                if (value && /\.((ino)|(cpp)|c)$/.test(value.trim())) {
                     return null;
                 } else {
                     return "Invalid sketch file name. Should be *.ino/*.cpp/*.c";