gui: modernize ChatEditWidget

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: remove polish comments from CustomInput class

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: remove unused enum from CustomInput

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: fix pasting urls into chat

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>