Add first submodule and scripts to update all submodules recursively

.gitmodules

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+[submodule "bolex_rewind_key"]
+	path = bolex_rewind_key
+	url = https://git.sixteenmillimeter.com/modules/bolex_rewind_key.git

bolex_rewind_key

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+Subproject commit 3b6ab71e9bad1c136483235d45d81431b9c3321f

init.sh

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+#!/bin/bash
+
+echo "Cloning all submodules recursively..."
+git submodule update --init --recursive

update.sh

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+#!/bin/bash
+
+echo "Updating all submodules recursively..."
+git submodule update --recursive --remote