New wiki backup

Signed-off-by: Samuli Seppänen <samuli.seppanen@gmail.com>
Updated cheiroballistra statistics spreadsheet

Signed-off-by: Samuli Seppänen <samuli.seppanen@gmail.com>
Added calibration formulae / archaelogical find comparison spreadsheet

Signed-off-by: Samuli Seppänen <samuli.seppanen@gmail.com>