Legends/plots became wrongly assigned when legend string was empty: drawLine did not "forget plot", but no legend entry was added
Axis label should be printed next to axis
Extract `warnAboutParamter` from `matlab2tikz`
Warn about the `noSize` parameter to fix #431

The `noSize` parameter will interfere with axes placement/sizing.
We should therefore warn the user about this
Extract `drawBackgroundOfAxes` from `drawAxes`
Move `view` option of 3D plots around
Extract `drawBoxAndLineLocationsOfAxes`

This simplifies `drawAxes`
Extract `drawLegendOptionsOfAxes` from `drawAxes`
Extract `imageAsPNG` from `drawImage`
Fix `imageAsTikz`: `m` and `n` not defined

These were forgotten during refactoring. Due to incomplete test coverage,
they were not discovered before.
Warn about `~imagesAsPng` parameter at the start

This causes the option to be printed only once, and is consistent with
different "dangerous" options.
Initialize `m2t.quiverId` by default
Renamed `{x|y|z|u|v|w}Data` in `drawQuiverGroup`
Extract function `getAndRescaleQuivers`
Extract `legendPosition` from `getLegendOpts`
Extract `legendOrientation` from `getLegendOpts`
Use `opts_add` in `getLegendOpts`
Handle `lStyle` in subfunctions of `getLegendOpts`

The subfunctions of `getLegendOpts` are now in charge of setting the relevant
legend style options. This way, superfluous checks are avoided
Extract `getFaceColorOfBar` from `drawBarSeries`
Extract `countBarplotSiblings`

This simplifies the `drawBarseries` function