Sending email search results is slow with poor user-interface

[japonicus]

Emailing frequency search results often gives no feedback after the email button is clicked - particularly for searches where the description generation is slow (e.g. long taxon lists).

After an email link click there should be an immediate 'email being prepared' dialogue box.

It should be possible to re-email or download emailed files from the search history page.

Email sending currently triggers a spurious empty tabular file download.