Change SendGrid.pm line-endings to unix, no content changes

fix write-excel.t - default xlscat separator no longer passes is() test using current Spreadsheet::Read, using defined ~ separator now; add .gitignore

* generate manual send() method to troubleshoot Email::SendGrid::V3 internals * validation of message data elements * default email address slurp() requires separate chomp() after switch to perl 5.36.0 - no idea why

add default self address; add sandbox and footer options to message object

first version of SendGrid