[TW-48] i18n: Weekend isn't always Sat/Sun

_Benjamin Podszun on 2012-02-16T15:25:07Z says:_

See subject: For a task management tool that shows beautiful reports I'd hope to have it recognize my weekend correctly.

Why? I'm an expat in Israel, I work Sunday to Thursday. There are other potential options [1], so I think this hardcoded behavior should go away.
Please add a configuration value.

I tracked the problem down (at least where I most prominently see it) in the code for the calendar report:

report.cpp, renderMonth(), line 1270ff:

```
// colorize weekends
if (dow == 0 || dow == 6)
cellColor.blend (color_weekend);
```

Please don't do that. Ask a locale aware library for the days that represents the beginning of the weekend (in which case I'd hunt down the required configuration elsewhere) or offer a setting equivalent to 'starting day of week' that allows me to define my work week.

1: https://en.wikipedia.org/wiki/Weekend