[patch] get_htdocs_dirs() method should return a unique prefix

[Jun Omae]

DataSaverModule.get_htdocs_dirs​ returns 'htdocs' as prefix. The 'htdocs' is a very common word.

I think that DataSaverPlugin should use datasaver. datasaver-prefix.diff​

[Steffen Hoffmann]

Replying to jun66j5:

![...] I think that DataSaverPlugin should use datasaver. datasaver-prefix.diff​

I think this too, as this is a universal rule, not only for DataSaverPlugin.

Thanks for catching this as is was certainly done by me by mistake. Must have been to busy looking for the special JS i18n implementation details for this plugin, so overlooked this.

No harm done by now, but if more plugins would resort to the unintended «htdocs» namespace, this could cause nasty effects. I'll fix it right away, before someone else copies this for his/her own plugin.

[Steffen Hoffmann]

(In [9406]) DataSaverPlugin: Correct indesired i18n namespace, closes #8005.

Thanks to Jun Omae for finding this and suggesting the solution right away.