Clean up two sets of code warnings relating to TextFieldListener:
(1) They were generally constructed with no effect (constructed but not assigned, which generates a compiler warning)
(2) They were constructed and passed "this" to another object (allowing "this" to escape a constructor is a warning due to a thread safety issue)

This takes out the listener assignment from the constructor thus solving both issues
Issue#: CODE-2426


git-svn-id: svn+ssh://svn.code.sf.net/p/pcgen/code/Trunk@23050 ef53c05b-3124-4d59-ae7d-fe3273f42be7