code cleanup (missing semicolons, redundant variables)
cleanup: remove remainings of unused offsetRow (now WalkontableViewportCalculator is used for that purpose)
move colOffset "calculation" back to Walkontable
cleanup: height & width are not part of Walkontable settings object since native scroll was implemented (now they are only defined as container size in CSS)
documentation
cleanup code irrelevant since switching to native scroll
refactor parameters of scrolling functions - now scrollTo, scrollHorizontal, scrollVertical and scrollViewport methods accept coordinates of the desired cell (not scroll deltas)
rename calculator, preCalculator to rowsCalculator, rowsPreCalculator; make room for colsCalculator, colsPreCalculator
documentation; logical code separation
cleanup tests
introduce new setting viewportRowRenderingOffset; rename viewportCalculatorOverride => viewportRowCalculatorOverride
fix after tests in IE8
shims for IE8
cleanup after tests