canvas_find dialog issues

The labels of the "Match Whole Word" checkbox and the "Search" button are currently hard-coded in pd_canvas.html. It would be nice if they could be made localizable. Sorry, I don't have an idea how to tackle that myself, so I have no translation merge request this time. :)

Also, when searching for multiple instances of the same search term, the find applet doesn't wrap around when the last instance is reached, like vanilla does. It seems to be stuck there, keeping on printing "... couldn't find" in the console, and it stays that way even when doing ctrl+f twice to start a new search.

There are other ways in which the usability of the Find applet could be improved. In particular, it would be cool to have up and down buttons to search for the previous as well as the next location of the search term. Moreover, it would be incredibly helpful if the found object, in addition to selecting it, could be made visible in the viewport by scrolling the viewport if necessary. Vanilla doesn't do that either and I'm not sure how difficult it would be to implement this with nw.js. But obviously it's really awkward for large patches if you have to scroll manually to locate the object that the find applet already found and marked for you.