[IMP] base_action_rule: merge _register_onchange() into _register_hook()
[IMP] base_action_rule: merge _register_onchange() into _register_hook()

Improve _register_hook() so as to patch only the necessary methods, and use the
fact that _register_hook() is always called on a "clean" registry.

optima-ict/odoo,stephen144/odoo,hip-odoo/odoo,sysadminmatmoz/OCB,bplancher/odoo,syci/OCB,storm-computers/odoo,tvtsoft/odoo8,ygol/odoo,storm-computers/odoo,laslabs/odoo,microcom/odoo,stephen144/odoo,mkieszek/odoo,optima-ict/odoo,hip-odoo/odoo,mkieszek/odoo,dfang/odoo,optima-ict/odoo,stephen144/odoo,ygol/odoo,sysadminmatmoz/OCB,mkieszek/odoo,bplancher/odoo,Elico-Corp/odoo_OCB,tvtsoft/odoo8,microcom/odoo,laslabs/odoo,sysadminmatmoz/OCB,laslabs/odoo,ygol/odoo,storm-computers/odoo,mkieszek/odoo,sysadminmatmoz/OCB,sysadminmatmoz/OCB,Elico-Corp/odoo_OCB,bplancher/odoo,dfang/odoo,microcom/odoo,laslabs/odoo,Elico-Corp/odoo_OCB,storm-computers/odoo,storm-computers/odoo,bplancher/odoo,tvtsoft/odoo8,ygol/odoo,dfang/odoo,tvtsoft/odoo8,microcom/odoo,Elico-Corp/odoo_OCB,dfang/odoo,syci/OCB,hip-odoo/odoo,storm-computers/odoo,Elico-Corp/odoo_OCB,microcom/odoo,dfang/odoo,ygol/odoo,mkieszek/odoo,dfang/odoo,ygol/odoo,stephen144/odoo,hip-odoo/odoo,syci/OCB,hip-odoo/odoo,optima-ict/odoo,sysadminmatmoz/OCB,laslabs/odoo,bplancher/odoo,bplancher/odoo,optima-ict/odoo,laslabs/odoo,Elico-Corp/odoo_OCB,tvtsoft/odoo8,hip-odoo/odoo,syci/OCB,mkieszek/odoo,optima-ict/odoo,ygol/odoo,sysadminmatmoz/OCB,stephen144/odoo,stephen144/odoo,syci/OCB,microcom/odoo,syci/OCB,tvtsoft/odoo8