* Stack Error shouldn't revert to previous state
* Updated VM Test tool
* Added Transfer method to VM Env

* CLI ethereum should no longer require the Qt/QML package

tests/vm: fix syntax

Improve package ethlog

Rather than spawning a new goroutine for each message,
run each log system in a dedicated goroutine.

Ensure that logging is still asynchronous by using a per-system buffer
(currently 500 messages). If it overflows all logging will hang,
but that's better than spawning indefinitely many goroutines.

Messages are formatted by generic part, so the log system doesn't need
to provide formatting. This fixes the test from the previous commit.

As a small bonus, log systems now have access to the level of
the message. This could be used to provide colored logging in the
future.

This test fails because the log message is formatted twice.

This ensures that examples will actually compile.

It's now safe for concurrent access.
Output checking looks better.

This also fixes a deadlock in the tests.

Blocking event package