Extract `getXYAlignmentOfText` from `drawText`
Extract `getRotationOfText` from `drawText`
Extract `getPositionOfText` from `drawText`
DRY in `getPositionOfText`

Quite some code was duplicated, now this has been simplified to a single
call.
Extract `getColorOfMarkers` from `drawScatterPlot`

This DRYs `drawScatterPlot` a bit
Extract `add3DOptionsOfAxes` from `drawAxes`
Extract `surfaceOptsOf{Surf,Mesh}`
Extract `addStandalone` from `saveToFile`

This removes quite a lot of checks in favor of single
`switch-case`. Everything related to `standalone` is thus
contained within this single function.
Extract `setAxisTicks`
Move `{get,set}AxisTicks` near to `getAxisOptions`

Their only caller is `getAxisOptions`, so they should appear near each other.
Extract `setAxisLabel` from `getAxisOptions`
Extract `setAxisLimits` from `getAxisOptions`
Extract `getColorbarPosOptions`
Merge `{get,set}AxisTicks`
Extract `assertValidAxisSpecifier`
Use `assertRegularAxes`

The replaced `switch-case` was nonfunctional in:
 - Octave 3.8.0
 - MATLAB R2014a
 - MATLAB R2014b
for our ACID testsuite: only the last branch was ever entered.
So it can be removed.

However, for safety, I've introduced the function `assertRegularAxes`
that makes sure that only that branch would ever be called.

In the odd case that some code would need this switch-case, we should
get an issue report in the future.
Merge branch 'simplify' into develop