enhancement idea: reverse search

[clach04]

Incremental forward search works great. It would be a useful feature to be able to search backwards.

It looks like repeating a search will loop around which is a semi-workaround for small files but not realistic for files with many matches. As there is a file size limit it may be reasonable to search the entire document and also include a count. E.g. 1 of 35 hits.

[billthefarmer]

Find previous doesn't work – see #225 (comment)