Use c4query_columnTitle to get column names

[pasin]

LiteCore has implemented c4query_columnTitle for getting column names. CBL should use that instead of generating the column names by itself.

[pasin]

This has been done as part of #2228.

[borrrden]

Is it just me or does this completely ignore aliases when generating column names? I think c4query_columnTitle needs to define exactly what it provides and what it does not.

[pasin]

@borrrden We have a key projecting test which also tests alias. Can you point me to .NET test that the alias doesn't work?

[borrrden]

This one fails. LiteCore returns '_id' for 'mainDocID' and '_id #2' for 'secondaryDocID'

[pasin]

@jayahariv Can you check on this?

[borrrden]

Furthermore, if a database has an alias, the improper name will be returned (the real name of the database instead of the alias)

[jayahariv]

seems like iOS tests are passing in both release/iridium and master