SubprocessOutputSequence.strings(): Different code in README, better documentation, and naming

[stefanspringer1]

1. Code in README differs:

README: execution.standardOutput.lines() (does not compile)
from the tests: execution.standardOutput.strings()

2. Better documentation

The documentation comment of strings() does not say if the separator will be contained in the strings. According to the corresponding test (stdout += line) it should to be the case. Please add this info to the documentation comment. (And if the separator is not contained in the strings, the test should maybe do something like stdout += line; stdout += "\n".)

3. Naming

I like lines() more than strings() (compare line in execution.standardOutput.strings() to line in execution.standardOutput.lines()).