Requirement-check not working with symphony 2.3.2

*Re-submitting against development branch on base repo (still learning git[hub], sorry ;)).*

**Original message:**
After checking why I couldn't save a section entry without adding an optional date (always getting the required-field error message) and checking the field settings array I found the check of the field's required-setting (in method "checkPostFieldData") to be faulty and fixed it.
I also changed the relational operator to type-comparing (===) in all conditionals to avoid other unforeseen effects and int-casted numeric field-settings at the same time if necessary.