[Keymap] Add issmirnov {user, ergodox, levinson} files. (#7239)

* Add issmirnov {user, ergodox, levinson} files.

There are enough interesting QMK tricks in these layouts that it seems
worth it to share with the broader community. Big thanks to Drashna for
inspiration, as well as all the wonderful creators of QMK documentation.

Some highlights:
- Common layout shared between levinson and ergodox_ez
- TAP_TOG macro for fast layer switching
- Autogenerated keymaps ascii art with git hooks

I will do my best to do periodic rolls here, but the source of truth
will always be https://github.com/issmirnov/qmk-keebs

* Incorporate review feedback.

- Remove CLEAR_EEPROM in favor of built in EEP_RST
- Remove custom handlers for audio on bootup and shutdown
- Remove plethora of unneeded includes
- Remove deprecated and dupliated config options

HUGE thanks to drashna for the review!

* Apply suggestions from code review

Huge thanks to drashna@ for a very thorough review and the very useful suggestions.

Co-Authored-By: Drashna Jaelre <drashna@live.com>

* Remove unclear optimization

This was an artifact from some other keymap I saw.

1 files changed, 10 insertions, 0 deletions

diff --git a/users/issmirnov/tap_tog.h b/users/issmirnov/tap_tog.h
new file mode 100644
index 0000000000..f59711f043
--- /dev/null
+++ b/users/issmirnov/tap_tog.h
@@ -0,0 +1,10 @@
+#pragma once
+
+#include "issmirnov.h"
+
+extern bool tap_tog_layer_other_key_pressed; // set to true if any key pressed while TAP_TOG_LAYER held down
+extern bool tap_tog_layer_toggled_on; // will become true if no keys are pressed while TTL held down
+extern uint8_t tap_tog_count; // number of presses on TAP_TOG_LAYER button.
+
+// Tap dance analog with momentary toggle when held, switch when tapped
+void process_tap_tog(uint8_t layer, keyrecord_t *record);