interface for constructing SQL queries

[zork]

Goal is to provide simple interface for constructing SQL queries similar to printf, but resistant to SQL injection problems.

Something like this:

dba::query sql("INSERT INTO table VALUES (%s,%s,%s)");
sql << myvalue1 << myvalue2 << myvalue3

operator<< would replace first %s found with myvalue1. Based on myvalueX type replacement should add quotes, escape quotes found in value or "%" char found in LIKE statements.

For compatibility with object serialization operator<< should accept StoreableFilter<T> derived types to easily convert custom types to int or string SQL values.

[zork]

some work on API, not branched yet

[zork]

Implemented in r229 and r230