Cleanup: Replace tabs with spaces

This commit replaces all tabs in *.ml[i] files with 2 spaces using

    sed -e 's/\t/  /g'
Cleanup: Remove trailing whitespace

This commit removes all trailing whitespace in *.ml[i] files using

    sed -e's/[[:space:]]*$//'
Cleanup: Remove trailing empty lines

This commit removes trailing empty lines from *.ml[i] files using

    sed -e :a -e '/^\n*$/{$d;N;ba' -e '}'
Add ocp-indent settings file
Cleanup: Run ocp-indent

Run `ocp-indent -i` it on *.ml[i] files.