Advanced search: improve form validation

http://dev.nysenate.gov/issues/7047

the advanced search doesn't handle any form validation at the initial form submission level. it's all done much later in the process when the query is being built and its run through data type functions like CRM_Utils_Type::escape().

that results in fatal errors for something as simple as placing a space in an INT type field. for example – place a space or alpha in the contact ID field.

We should at least implement some form validation for INT fields and other numeric fields – including custom data fields – and return the user to the form rather than throw fatals.