Multiple chart fixes

# Incorrect output when multiple *header* columns

If more then one level or hierarchy is used for columns, chart output is incorrect. Turns out only the first row of top-level hierarchy was visible. Take the following report on *Sales* cube as an example:

![report](https://f.cloud.github.com/assets/164045/74442/9d1fb8a0-6091-11e2-8796-4bc3c78dcd2f.png)

## Before:

Only *Q1* is shown.

![before](https://f.cloud.github.com/assets/164045/74443/a40002ba-6091-11e2-9cb0-b51dfc932310.png)

## After:

All rows are shown:

![after](https://f.cloud.github.com/assets/164045/74445/a9918082-6091-11e2-9342-bdca9f462995.png)

Looks like the same bug (if it works as expected, it's waaay to confusing) is present when multiple header rows are selected, but I didn't manage to fix it.

# `[NN]` counter optional

Previously every label on X-axis had a counter, e.g. *"Virginia [1] | Oregon [2], ...* Now it's added only if there are duplicated labels on the chart.

# Stacked bar empty when some data unavailable

Sometimes when some cells in report are empty, stacked bar doesn't display anything. It's fixed by implicitly placing `0` in such cells.

For example in *Sales* cube put *Month* in columns and *City* (from *Customer* dimension). Stacked bar is invisible without this fix.

# More colors

Increased the number of distinct colors from 5 to 11 (based on default jqPlot pallet).