#2 Fixed exception chaining in PluginException.

[Grzegorz Lukasik]

All constructors for PluginException do not hadle cause
of exception properly. All of them have something like
that:

public PluginException(IllegalAccessException e) {
this.cause = e.getCause();

It shoud be:

this.cause = e;

Otherwise many useful information about stack trace is
lost.
Attached patch fixes it.

[Grzegorz Lukasik]

Patch for all PluginException constructors.