Icons for Text Properties dlg box

TEXT PROPERTIES dlg box: icons for horiz. and vert. alignments with higher contrast and clearer design.

A separate icon for baseline alignment is also added.

Before and after:

![text_props_before_and_after](https://f.cloud.github.com/assets/1420743/491327/b9f3df0e-ba16-11e2-86b0-67794d28ff39.png)