Doc
More clever algorithm for setting range

Old one failed to add padding properly in some circumstances.
Add padding correctly for plots in log scale
Fix padding
Remove debug printing
Fix misleading documentation
Remove useless initialization
Fix issue with canvas resizing

Canvas size wasn't recalculated after `clear'
Use shared ptr
Accept more spellings
Update README
Fix warning
Add automatic iterpretation of 4-column data
Prepare for parsing data with asymmetric errors
merge
Parse asymmetric errors for graphs
Missing return
Add type class for rendering of graphs with errors
bump