Add option to build SQL*Loader control files

[roskakori]

Goal: cutplace --sql sqlldr some_icd.ods buils a script that can be passed to sqlldr to load data conforming to the CID into a table.

sqlldr documentation:

• command line usage: http://docs.oracle.com/cd/B19306_01/server.102/b14215/ldr_params.htm
• concepts: http://docs.oracle.com/cd/B19306_01/server.102/b14215/ldr_concepts.htm

Note that control files cannot express that the last field in a CSV can be empty; it either has to be empty all the time or never. Consequently cutplace must fail if the last field has x in the Empty? column but is not a ConstantFieldFormat