Trader prevents Buy triggers when buying Silver

Because, if it sees a Silver about to be gained, it
returns `nil` instead of a valid action.
Improve button text for unidirectional Develop

When using Develop on a card for which no pile exists
which is one cheaper, or no pile which is one dearer,
the button text is now less confusing.

Fixes #82
Cause Oracle log for discarding to be striped

Removed a stray comma which was making the first CSS class wrong
Fixes #85
Remove gender-specificity from two logs