Frontend updates

The register form is included. Three events are also added. (1)
clicking the link in the login slide-in menu (top right) opens the form
and shows the overlay. (2) clicking the 'close' button on the register
form closes the form and hides the overlay. (3) click the register
buttons shows line to console.
Als menu.png is adjusted to include the new input field backgrounds,
close button and register button.
Sidenote: also updated charts.js. Switched from object datapoints to
array datapoints, removing the max limit for turboThreshold parameter.
Also changed the 'add new datapoint' timer to use a global var
(currentY) to add as new datapoint every second. A Pusher message can
now set the currentY variable to the new stock price that is being
pushed, and the add datapoint function will pick it up automatically.
Needs to be improved, as only the first graph is now supported. Will
change to array ( currentY[0], currentY[1]…. currentY[n] ).
Some code cleanup.