Per column (property) and per document (class) formatting

[jordangray]

Consider options for adding per column and per document formatting. Can't use a lambda in the attribute, so would require declarative syntax somewhere or choosing what formatting options to allow and adding them to ExcelAttribute.

[jordangray]

Idea: add classes (e.g. ExcelColumnFormat, ExcelDocumentFormat) which provide appropriate properties corresponding to various formatting options; these can be subclassed, and the type can be passed as an argument to the corresponding attributes:

[ExcelDocument(format=typeof(FinancialReportFormat)]

Personally, this seems like the most elegant way of extending the formatting options provided to the maximum degree possible while retaining the current practice of decorating classes with attributes.