fixed include for SourceRange.hpp
support OffsetConverter should return offset in the first line
support OffsetConverter should return offset from the last eol as col
support OffsetConverter should return number of eols till offset as row
support OffsetCoverter should fail if offset is greater than the text size
replaced global variables with member variables in steps
runner takes row/col as location instead of offsets
refactored extract_function.cpp
made include directories absolute