rename test "one_point" to "multline_labels"

* extend test to also include a multiline legend
* make sure this also works, if a second plot is present
* clean up test, change description
Split legend if newline character is present

The newline character can be used to create multiline legends.
To be treated properly, the legend string needs to be split into a cell array.

References:
* http://www.mathworks.com/matlabcentral/answers/101117
* http://www.mathworks.com/matlabcentral/newsreader/view_thread/41504
Improve style of warning
Fix legend options and handle alignment correctly

* fix "legend plot post" to "legend plot pos"
* add option "align" to correctly handle multiline nodes (see Chapter "17.4.3 Text Parameters: Alignment and Width for Multi-Line Text" of pgfmanual)
* remove wrong option "nodes"
* do not set "legend plot pos" explicitly, since default is 'left' and thus ok
Improve test title and extend test case

Add different types of newline
* cell array
* sprintf with newline character (= ASCII 10)
Fix multiline labels in R2014a
Fix name of error source
Adjust formatting
Fix multiline legends for R2014a and R2014b

It seems to be not possible to determine if a legend entry is messed up in R2014a. As such it is recommanded to use the `sprintf` approach to add a new line in the legend. This works in both R2014a and R2014b.
move linefeed detection to proper function
revert a formatting change
Optimize pull request

* Remove need for new matlab function `strsplit`
* Remove need for transposing cell array. Array `strings` is now looped with linear indexing.
Merge pull request #439 from PeterPablo/multiline_legend

Tested in R2014a and R2014b by @PeterPablo