make sure bogus filters don't kill us
iconv doesn't throw exceptions, but we can safely ignore all notices here because the point of this is to probe for the best charset (so errors are to be expected)
defer reading the file until we checked the upload result / turned accidental global detect_encoding function into an anonymous one

detect_encoding() doesn't seem to be used by anyone outside this controller. Check all plugins
known to me.
fixed deleting charts

The static path contains not only files, but also sometimes an assets directory. In any case,
this code is more stable, though not as pretty.
turned off first row fixing in data table, fixes severe bug
allow hiding of admin pages in menu

..by setting "hide" to true
pass url arguments to admin page controller
changelog, bumped version
Merge branch 'release/v1.8.2'