Fixed variable names for SQL functions to allow to call these directly from Tcl
---
--- Fix SQL function that were defined with the same number of
--- arguments and the same argument names, but receiving different
--- types (integers vs. timespans). This is fine, as long the
--- functions are only called from SQL and positional arguments. When
--- calling from Tcl, this does not work.
---
--- This change uses in cases, where offsets are specified as
--- intervals the suffix "_interval" for the variable names, keeping
--- the names without this suffix for integer arguments (for Oracle
--- compatibility).