This commit fixes a few (mostly) small issues:

* Fixes a fairly annoying issue, which causes the buttons in the secondary toolbar to become messed up when they overflow the max-height of the container (since the scrollbar needs to be displayed). This fix causes the width of the secondary toolbar to become slightly larger than technically necessary, but this was the only solution I managed to come up with that only required CSS (and no JavaScript). Since other panel are fixed-width, I think it might be OK (looks good at least to me, but I'm not an UX designer).

* The 'max-height' property of the button container in the secondary toolbar need to be dynamic, so that it works properly with different screen sizes. Since there doesn't seem to be a good way to achieve this using only CSS, I added a function in secondaryToolbar to solve this.

* Cleanup some of the CSS rules, to avoid unnecessary duplication.

* A small amount of improvement of the secondaryToolbar method in viewer.js.

* Moves the text on the buttons down one pixel, since this looks better compared to the vertical center of the icons.

* A few slight changes of the padding in the secondary toolbar, to avoid some unnecessary waste of mostly vertical space (makes sure more fits on smaller screens).

* Reverses the order of "rotate clockwise" and "rotate counterclockwise", since this seems like a more logical ordering.