That's a horrible idea Robert, sorry.
You would end up with dozens of different ways to call the same
function. Plus libraries incompatible without that option set. But I
will center in a much clearer problem: suppose you need to look up where
is somefunctiontocheckusername() called. Is it called as
'somefunctiontocheckusername', 'some_function_to_check_username',
'some_function_to_check_user_name', 'some_function_to_check_userName',
'someFunctionToCheckUsername', 'someFunctionToCheckUserName',
'SomeFunctionToCheckUsername', 'SOMEFUNCTIONTOCHECKUSERNAME', or maybe
's_o_m_e_f_u_n_c_t_i_o_n_t_o_c_h_e_c_k_u_s_e_r_n_a_m_e' ?
And no, even if you have an über PHP editor which knows how to handle
it, there are cases when you are in a remote system, remotely connected
to the server... and loading a full project into a big editor for a
function search is not practical. While every (decent) editor is able to
make a case insensitive search.
If you really want to rename core functions in your own system, you can
do it with runkit... But remember runkit motto: «For all those things
you.... probably shouldn't have been doing anyway....»
