Add buttons to change the maxvotters field
Increase even more the max votters font size
Move the title to the chart canvas
poll screen: center radiobuttons, set right margin
new poll: disable next button in the last page
New poll: limit max chars in the fields, improve summary on long texts
Charts refactoring

The labels in the bars need be moved to the bottom of the bars,
then the code is completly different. Separate the drawing
of every chart.
charts: more reorg, move measure and print title to separated methods
charts: move labels in the bars to the botom
charts: fix vertical center of labels, limit max label size to 30 chars
Better spacing on poll screen
chart: adapt title font size to dpi resolution
chart: improve horizontal center