Keymap: Redox / jeherve: updates (#4694)

Keymap: Redox / jeherve: updates (#4694)

* Start using send_unicode_hex_string for shrug

See https://docs.qmk.fm/#/feature_unicode?id=send_unicode_hex_string

* Make sure one can come back to main layer after tapping to NAV

* Add 4 new keys to symbol layer

~, `, =, +, are now more accesssible. No need to reach out far from home row anymore

* Add two new macro keys

I did not have much use for the Expose key and the right Command key, so opted to replace those with 2 Macros:

- One to invoke Alfred: https://www.alfredapp.com/ => Opt + Space
- One to invoke 1password: https://1password.com/ => Cmd + Opt + \

* Update readme to mention changes in new version

* Remove unneeded short definition

* Shorter name for our custom key

See https://github.com/qmk/qmk_firmware/pull/4694#discussion_r243341864

* Make macros one-liners

See https://github.com/qmk/qmk_firmware/pull/4694#discussion_r243341487

* Switch to using eeconfig_init_user to set Unicode mode

See https://github.com/qmk/qmk_firmware/pull/4694#issuecomment-449151724