Introduce Verbose Logging

[mbaker3]

Introduce a method of emitting logs only when an ANVIL_LOG_VERBOSE directive is present.

This should still allow for Error, Warning, Debug levels within the verbose log and should probably take the form of a VerboseLogger object that wraps Logger.

Keep in Mind

When ANVIL_LOG_VERBOSE is not present

• Verbose logger should occupy no or minimal memory
• Verbose logger message emitting calls (Debug, Warning, etc...) should not execute. Preventing the message string from being allocated (use ConditionalAttribute)

Ideas

• Place a verbose logger instance inside of Logger so usage would be something like Logger.Verbose.Warning()
• Have verbose logger live alongside the Logger getter in AbstractAnvilBase