Improve Org commands

- Optimize `org-save-buffer-and-do-related'
- Add custom view "rr" for "Recent items (past 7 days)"
- Rename `leuven-org-todo-list-current-dir' (bound to <C-f3>)
- Simplify Latexmk command: "latexmk -CF -pdf -pdflatex=xelatex %f && latexmk -c"
Use the SMIE code for navigation and indentation