All new rendering pipe line

- processing files is made similar to rendering template files: call an appropriate function based on the type of file (its role more precisely)
- the state of the source directory is recorded so that only changed files need to be rendered
- implement a watch() function which takes advantage of this to process the changed files at a given time interval
- render is now called build; rendre has a new meaning
Roxygen update
Add TODOs
New function toggle_attribute
Remove extraneous import
Bootstrap form generating functions