Last find text should be global across all cursor managers

[jteh]

The last find text (used by find and findNext) currently only applies to a single cursor manager instance. This means that each time a new cursor manager is used (e.g. for every new document when browsing the web), the last find text is lost and must be re-entered. Often, one wants to do the same search on several pages, so this is rather painful. The last find text should be global across all cursor managers instead of being separate for each instance.

[jteh]

Implemented in r1859.