Comment 17 for bug 408093

Another patch for the following new typos:

1. share/extensions/draw_from_triangle.inx.h:35 (in the long description)
"an formula" -- a
2. share/extensions/draw_from_triangle.inx.h:
"a circle about a custom point" -- around
3. share/extensions/polyhedron_3d.py:
msgid ""
"Failed to import the numpy module. This module is required by this "
"extension. Please install it and try again. On a Debian-like system this "
"can be done with the command, sudo apt-get install python-numpy."
 -- would be better if the command was between quote marks, and without the comma.

Also added a revert for a bad fix in the previous patch (incorrect disambiguation in INX files, "Top" is now disambiguated in layers.cpp - Bug #426703) and a new string added to translation files (the default "filter" string for a new filter in the editor is now translatable).