PATCH: Format SQL (external tool)

Hello All!

Per discussion
http://www.postgresql.org/message-id/CAPyomk5NT9Tm-r3wombLzoY60Vqa+QyRDy4u84_2K9UWLbWHTg@mail.gmail.com

It's most useful for making readable queries generated by ORMs such as
Hibernate. But in general, external processing can go far beyond
formatting task.

I've implemented this feature quick-and-dirty long ago. Finally I made
myself clean it up, now it looks better, so please consider a patch.
Tested on Windows 7 and Ubuntu 14.04.

Changes:
* added new setting, ExtFormatCmd, "External formatting utility" in
  Options dialogue
* added menu item "Edit - Format - External Format" in
  Query editor
* class sysProcess supports UTF-8 and can pass STDIN for a process.

Suggested use scenario:
1. Download and install some SQL formatting utility.
2. Tell pgAdmin where it resides:
   File - Options - Query Editor: External formatting utility.
3. Open Query editor. Select a text block to format and press
   Ctrl-Shift-F. With no selection the whole text gets formatted.
   In case of non-zero exit code, STDERR will be shown in status bar.

Requirements for external formatting utility:
* Accepts a STDIN stream and writes result to STDOUT
* Finishes in less than 3 seconds
* Exits with code 0 on success
Support for UTF-8 multibyte characters is preferable.

To see whether it works well, a test can be done:
C:\> type in.sql |some_formatter >out.sql
C:\> echo %ERRORLEVEL%
or
user@linux:~$ cat in.sql |some_formatter >out.sql
user@linux:~$ echo $?

There are few available utilities depending on platform:
   * Free SQL Formatter (Linux, Windows, Mac OS X(?))
     http://fsqlf.sourceforge.net/
   * Poor Man's T-SQL Formatter (Windows)
     http://architectshack.com/PoorMansTSqlFormatter.ashx
Also it is possible to make a wrapper script for numerous online
formatting services, but it's less secure and less reliable.

Fsqlf is FOSS and seems promising. I think of extending it for
PosgreSQL-specific SQL syntax and probably even PL/pgSQL.


--
Best regards,
 J.F.