AxisToIndex converts excel coordinates to to generical indexes.

ColumnToIndex converts an excel column name to his index, if the name contains special chars or numbers returns -1.

IndexToAxis converts 2 int coordinates to excel coordinates.

IndexToColumn converts an index (starting at 0) to a excel column: 0 -> A 1 -> B 26 -> AA 27 -> AB 52 -> BA if the index is negative returns empty.

IndexToRow converts the generical Index numeration to excel numeration - generical numeration starts at 0 - excel numeration starts at 1.

OpenOrCreateSheet checks if the excel sheet exists if exists set it as active otherways it creates it and then set it as active.

RowIndexToAxis converts a row index and a column (already given with excel coordinates).

IndexToRow converts the excel numeration to generical Index numeration - generical numeration starts at 0 - excel numeration starts at 1.