fix form size for NewField dialog

Original Reporter info from Mantis: alexs75

• Reporter name: Lagunov Aleksey

Description:

use autosize and anchors

Mantis conversion info:

• Mantis ID: 35249
• Version: 2.1 (SVN)
• Fixed in version: 2.1 (SVN)
• Fixed in revision: 60733 (#f414bde3)
• Monitored by: » alexs75 (Lagunov Aleksey)
• Target version: 2.0.2