Internal Boost Build testing framework cleanup - expecting output/content lines now correctly interprets requests with lines given as a container of strings.
Given strings represent expected continuous line sequences (separated by \n) and extra lines are allowed between content represented by different successive strings. For example, lines = ['foo\nbar', 'baz'] would match:
aaa
foo
bar
bbb
baz
ccc
but would not match:
aaa
foo
xxx
bar
bbb
baz
ccc
Added a description comment for the related Tester.expect_lines() implementation function.