Miscellaneous small fixes

Hi,

This time a patch that includes a lot small fixes. They come mostly
from going through a findbugs report. For each issue that I though was
valid I tried to always do the minimal fix. If some fix categories are
not wanted I can create a patch with the requested parts removed.

Here's a list of small things I changed. The patch itself was a few
kB too large for the mailing list and I had to place it here
http://mokki.dyndns.org/~mtiihone/postgresql/cleanup/

AbstractJdbc2DatabaseMetaData
- comparison of string parameter using ==
- many createStatement calls without statement.close().
- used new String("constant")

AbstractJdbc4ResultSet
- infinite recursion loop

AbstractJdbc23PooledConnection
- null assigned to parameter instead of field.
  UNCERTAIN if this is correct or if the line should have just been removed
- made static fields final

AbstractJdbc23SimpleDataSource
- removed unused imports
- made abstract so that serialVersionUID is not needed even though
  Serializable is implemented

AbstractJdbc2Array
- removed unused fields: idx and rs

AbstractJdbc2Connection
- use explicit US locale in toUpperCase
- removed unused imports

AbstractJdbc2ResultSet
- made NullObject static inner class
- changed locale dependent toLowerCase+equals to equalsIgnoreCase
- use explicit US locale in toLowerCase
- removed unused imports
- fields selectStatement, insertStatmenet and updateStatmenet removed because
  they were only used inside one method and never reused
- close deleteStatement on result set close
- refreshRow was not synchronized while other similar updateableResultSet
  methods were
- added double quotes and escaping to all tables names and primary keys in
  updateable stuff
- changed column escaping of generated updateble statements to honour
  escaping settings

AbstractJdbc2Statement, AbstractJdbc3ResultSet, AbstractJdbc4ParameterMetaData,
LargeObjectManager, MakeSSL, PGXAConnection, QueryExecutorImpl,
ServerErrorMessage, test code
- removed unused imports

Base64
- removed unused private method

ConnectionFactoryImpl
- made SimpleResultHandler a static inner class

EscapedFunctions
- use explicit US locale in toLowerCase

LargeObject
- commented out empty finalize method, its existence still slows down the JVM

NonValidatingFactory
- removed unused imports
- made inner class NonValidatingTM static

PGmoney, PGobject, RecoveredXid
- defines equals but not hashCode

PGinterval
- added missing synchronize around static DecimalFormat

PSQLDriverVersion
- made version number final

UnixCrypt
- Fixed wrong assumption that Math.abs never returns negative numbers