Establishes plain-text currency formats for e-mails and other plain-text contexts

Previously e-mails were sent out using the regular currency format, which often contains HTML entities. Since the e-mails are sent plain text, the user would see the entities instead of their equivalent characters.

This commit adds a way to retrieve plain-text currency formats and ensures updates email_tickets() to use them.
Revert "Establishes plain-text currency formats for e-mails and other plain-text contexts"

This reverts commit 067b2801513ade1167a2b38e9ee58bbe85128a2a.

Will use Unicode characters instead of the approach taken in 067b2801513ade1167a2b38e9ee58bbe85128a2a
Replacing HTML entities with their Unicode equivalents

Replaces previous approach to HTML entity problem in 067b2801513ade1167a2b38e9ee58bbe85128a2a