Make the stored data about pull operations fieldmap-specific, preventing problems when multiple fieldmaps are connected to the same Salesforce object. Thanks to WordPress user @fortafy for the report.

[jonathanstegall]

What does this Pull Request do?

When records are pulled from Salesforce, values are saved to the options table so the plugin knows what it has already done. This makes those records fieldmap-specific where it's appropriate, making multiple fieldmaps connected to the same Salesforce object more reliable. This fixes #414.

How do I test this Pull Request?

• Create two fieldmaps that pull from the same Salesforce object type.
• Turn on debug mode
• Update records on those Salesforce objects
• Inspect the SOQL queries.