fix DOMContentLoaded in async script
adds an email link to the footer
Numeric cell: Always revert numeral.language() to previous value.
Otherwise we have inconsistencies displaying numeric fields where `language` is not explicitly set.
Don't assume english when parsing numeric cells.
Instead, rely on the current value of numeral.language()

E.g.: My application sets the locale globally using `numeral.language('pt')`
Numeric cells should parse "International numbers" (Numbers using '.' as a decimal delimiter) with any number of decimals.

(Current implementation accepts '0.00', but fails on '0.0')
When copying, use the decimal delimiter from the user's locale.
(This defaults to '.', so there is no need to worry)

This is the same trick used to fix https://github.com/handsontable/handsontable/issues/1817