Add generated JavaScript file to project browser.

Use ProjectBrowserUpdater from NuGet Package Management addin.
Update readme.

Add note on new feature - generating JavaScript file on saving a
TypeScript file.
Display TypeScript compiler messages in Output window.

Show all compiler messages in the Build category of the
Output window.
Report TypeScript compilation failure in Output window.
Do not add JavaScript file if compilation fails.

If the TypeScript compiler fails then no JavaScript file
will be generated.
Add basic code completion for functions.

Show function parameters and overloads when the open
brace character is typed into the text editor.