Version 0.5.0

Added

• [BC] Add assert.Assertion.End()
• Add engine.Run() and RunTimeScaled()
• engine.Engine now protects its internal state with a mutex, allowing concurrent use

Changed

• [BC] assert.Should() now provides an assert.T to the user instead of checking the error return value
• [BC] Rename assert.Assertion.Prepare() to Begin()
• [BC] Add verbose parameter to assert.Assertion.BuildReport()