allow input methods to send "<"

[bfredl]

when sending text input to neovim, there is this special case to handle. Compare the ime event handler in python-client:

    def _gtk_input(self, widget, input_str, *args):
        self._bridge.input(input_str.replace('<', '<lt>'))

[rhysd]

I understood what had happened.

Although this fix is not enough, we can start here. Thank you!

[bfredl]

What is missing? I thought, to input unicode text to neovim, only < needs to be escaped (this is what the gtk client does)

[rhysd]

Input method. For example, When Japanese input method is enabled, '＜' should be input but actually '<' is input. ('＜' is different from '<') No problem, I already added fix at the latest commit.