Fixed issue #155
continuation lines are now calculated from the logical indent level
(1 tab = 8 spaces, as calculated by `expand_tab`)
not the physical number of whitespace characters
(which will only be the same if indents are only defined with spaces and not tabs)
Merge pull request #156 from harvimt/f97a1c1605a14bee3115070e836d7ad491c41656

Expand tabs when checking E12 continuation lines. Issue #155