Move some of the fields in a GncPluginPage from the public to the

[David Hampton]

Log Message:
-----------
Move some of the fields in a GncPluginPage from the public to the
private data structures.

Tags:
----
gnucash-gnome2-dev

Modified Files:
--------------
    gnucash/src/gnome:
        gnc-plugin-page-account-tree.c
        gnc-plugin-page-register.c
    gnucash/src/gnome-utils:
        gnc-main-window.c
        gnc-main-window.h
        gnc-plugin-page.c
        gnc-plugin-page.h
        gnc-window.c
    gnucash/src/report/report-gnome:
        gnc-plugin-page-report.c