Add some additional scenarios to Excel append tests:
- Non-A1 start
- Name duplication
- Hitting another range
# Important Notes
Also fixed a warning in the Image library.
Adds support for appending to an existing Excel table.
# Important Notes
- Renamed `Column_Mapping` to `Column_Name_Mapping`
- Changed new type name to `Map_Column`
- Added last modified time and creation time to `File`.
- Read in Excel files following the specification.
- Support for XLSX and XLS formats.
- Ability to select ranges and sheets.
- Skip Rows and Row Limits.
# Important Notes
- Minor fix to DelimitedReader for Windows
