Improve error message importing native declaration - #871
Importing a native declaration as []int{}, Scriggo returns the error
importing package main, declaration "toc" is not valid
It is not clear why it is not valid. This change reports instead:
cannot import toc: to import a variable use a pointer to that variable
Update README file
Improve the example on templates, add a padded version of the logo and the badge for 'Go Report Card'