#12 PluginFileLocator should handle parse errors in a better way

[Thibauld Nion]

PluginFileLocator should handle plugin parse error in a better way, by reporting more clearly what caused the parse problem.

This is especially needed for the python3 branch, because configparse is now strict by default.

See also: https://github.com/tibonihoo/yapsy/pull/1

[Thibauld Nion]

actually there are already logs for parsing problems, so a little more sanity check should avoid having strange internal exception callstack

[Thibauld Nion]

Fixed in v1.10.323