Reusability of handler helper methods

[ctgraham]

Methods TextureHandler::_createDependentFile() and TextureHandler::_updateManuscriptFile() seem reusable enough that they could be methods of the Plugin, or even of SubmissionFileManager.

For example, for #32, we would want a plugin hook to potentially do both of these things. There would be no need to reach out to a Handler.

@withanage , @asmecher , opinions on whether to promote these methods to the plugin or to SubmissionFileManager? Are there assumptions or specifics I'm missing here which limit the reusability of this code?

[ctgraham]

Also, this transformation of mime type to genre: probably not robust enough for GenreDAO, but should we stub it out in that direction?

texture/TextureHandler.inc.php

Lines 177 to 199 in bbac9e8

	import('classes.file.PublicFileManager');
	$publicFileManager = new PublicFileManager();
	$journal = $request->getJournal();
	$genreDao = DAORegistry::getDAO('GenreDAO');
	$genres = $genreDao->getByDependenceAndContextId(true, $journal->getId());
	$genreId = null;
	$extension = $publicFileManager->getImageExtension($media["fileType"]);
	while ($candidateGenre = $genres->next()) {
	if ($extension) {
	if ($candidateGenre->getKey() == 'IMAGE') {
	$genreId = $candidateGenre->getId();
	break;
	}
	} else {
	if ($candidateGenre->getKey() == 'MULTIMEDIA') {
	$genreId = $candidateGenre->getId();
	break;
	}
	}
	}

[ctgraham]

Concrete example (if we want to keep it to the plugin):
ulsdevteam@b461f23