NH-3094: Support unary minus and plus operators in LINQ

[PleasantD]

Fixes NH-3094

[fredericDelaporte]

The UnaryPlus test failed with Firebird, relevant error message seems to me:

  Name:p1 - Value:2  Name:p2 - Value:9
[SQL: select cast(count(*) as INTEGER) as col_0_0_ from TimesheetEntries timesheete0_ where timesheete0_.NumberOfHours+@p0=@p1]
  ----> FirebirdSql.Data.FirebirdClient.FbException : Dynamic SQL Error
SQL error code = -804
Data type unknown

[PleasantD]

I removed the unneeded Add expression from the UnaryPlus test. Firebird should run fine now.

[hazzik]

👍