adding lambas to select statements for customer lists and reports

[SethHamilton]

Providing an easy way to enumerate all the customers in a segment created with a /segment query. A customers query will sort on a list of result columns as defined in the select statement. These may be existing customer properties or values created by evaluating customer events.

The result set will contain the number of customers requested, as well as a cursor that can be passed back to OpenSet on a subsequent query to continue where you left off.

• [x] lambdas in select statements. This is required to get variables and inline aggregations as return values from a customers query script
• [x] short-cut lambdas for selecting a user variable in a script (lambda is created it not provided)
• [x] add compile mode flags to return meaningful errors depending on the purpose of the script (reports, segments, customers)
• [x] rename event query to report. This is more inline with other query types (i.e. segment, customer, customers, property and histogram.
• [x] customer lists with pagination (trim and starting point)
• [x] optimize customers query to shortcut running actual script if values are can be calculated from customer properties.