Fix for Bug #137168 (Update Columns in inkscape default palette).

The LaTeX beamer class is the new latex standard to produce slides: http://latex-beamer.sourceforge.net/ It produces custom sized pages and includes several layout/color themes. I added an Inkscape template document with the correct page dimensions as well as guides to delimit the text area within the slide for several themes, in order to ease the production of illustrations at correct sizes (scalability is great but having the correct size from the start limits issues with stoke width and font sizes for example). I also constructed a color palette which includes colors suitable for each theme of the standard beamer package. I am no color-expert/artist so I don't really know about the rules in this delicate subject. What I did is that for each theme I extracted the base colors of the slides with a color picker tool; I named them according to their use in the slide (eg. "{themeName} header", "{themeName} background"); when I found this base color set to be a bit poor, I added new colors derived from the original ones by mixing them with white, black, with other colors in the theme or by using automatic color schemes generators; I named these new colors "{themeName} added {colorName}". hopefully this should have led me to avoid bad color choices.