Fix #75

Where all the posts would be serialized

Fix #71

Close #67

Fix #66

Fix #59

Also add a Site::render_section method

Useful if you're creating a section only to access it in the index but
do not want a section page for it

Closes #14, #43

Avoid issues with temp files from some editors

Also fix gutenberg serve that has been broken (not
re-rendering content) for quite some time now.

Copy only static files that triggered the change notification

To every templates, useful when doing
navigation to know which link is currently
active