Stopped VehicleTest from behaving erraticlly,

by ensuring the fixture cannot return 4; the default value that would indicate the property was *not* populated.
Added a failing test, demonstrating issue #262,

the TracingBehavior / TracingBuilder incorrectly reports the Depth after a previous request threw an exception.
Fixed TracingBuilder Depth reporting.
Added test to verify Depth of TracingBuilder after exceptions
Merge branch '259-erratic-vehicle' of https://github.com/adamchester/AutoFixture into adamchester-259-erratic-vehicle
Improved TracingBuilder Create logic,

to make it more readable.
Merge branch 'fix-trace' of https://github.com/adamchester/AutoFixture into adamchester-fix-trace
Incremented patch version,

in order to indicate that the correction of TracingBuilder indentation is
a bug fix. This resolves #262
(https://github.com/AutoFixture/AutoFixture/issues/262).