Write FieldDefinition UseCount; null check on FieldObject.DataSource
tabify
Fix #9
Merge @slestak condition formulas work

Implement several condition formula elements

Conflicts:
	RptToXml/RptDefinitionWriter.cs

Closes #8
Implement several condition formula elements

Conflicts:
	RptToXml/RptDefinitionWriter.cs

Closes #8
Implement several condition formula elements
Merge branch 'slestak-AddConditionFormulas' of https://github.com/ajryan/RptToXml into slestak-AddConditionFormulas

Conflicts:
	RptToXml/RptDefinitionWriter.cs