chrono: add tick, double-tick and double-dot segments.
chrono: implement a 7-segment display renderer.
added a command to see the session start time. also added a prompt.
added new training sessions for weights and skills cycles/periods.
added an archival tool. updated the default calisthenics session.
added new exercises. sanitize all input. got rid of the default session and included a calisthenics routine instead.
workout: ignore shell-style comments from input when adding reps per exercise.
add more exercises, the default session file and better explanations.
remove unnecessary (and confusing) parentheses.
make bmr a script and add new exercises.
only register the exercises you actually did