Improve apex bind variable parsing #155

[paustint]

Improved support for apex expressions

Added test-cases for the following queries:

• SELECT Id, (SELECT Id FROM Contacts WHERE Id IN :contactMap.keySet()) FROM Account WHERE Id IN :accountMap.keySet()
• SELECT Id, (SELECT Id FROM Contacts WHERE Id IN :contact_900Map.keySet()) FROM Account WHERE Id IN :acco INVALID untMap.keySet()
• SELECT Id FROM Account WHERE Id IN :new Map<Id, SObject>(someVar).keySet()
• SELECT Id FROM Account WHERE Id IN :new Map<Id, SObject>(someVar).getSomeClass().records
• SELECT Id FROM SBQQ__QuoteTerm__c WHERE SBQQ__StandardTerm__c = :CPQ_Hard_Coded_Ids__c.getInstance().Standard_Quote_Term_Id__c
• SELECT Id FROM Opportunity WHERE SBQQ__StandardTerm__c = :quotes[3].SBQQ__QuoteLine__r[0].Term__c

resolves #155