Replace invalid characters - Fixes #3

Replace invalid characters with underscore
Updated formulas - Fixes #2

Updated the IFERROR statement in  the formula for "PO Number"
Updated the IFERROR statement in  the formula for "Release"
Updated the IFERROR statement in  the formula for "Route Code"
Updated the IFERROR statement in  the formula for "Invoice Number"
Updated Plant Name formula - Fixes #1

Added IFERROR and IF(VLOOKUP=0) to "Plant Name" formula
Incremented Version