Contextualize ValueResolvers and ContextResolvers, improve response handlers

Contextualization:

• ContextResolvers and ValueResolvers now accept a single parameter, ContextResolverContext and ValueResolverContext respectively.
• Both contexts extend from ParameterResolverContext, which exposes the CommandActor, CommandParameter, as well as other useful elements
• Contexts provide the ability to refer to the arguments that have already been resolved.
• Contexts should make it easier to introduce additions to resolvers without breaking old code
• This update is not backwards-compatible!

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• Automatically infer responses of type java.util.function.Supplier
• Fix response types not allowing nesting, for example a CompletableFuture<Optional<String>>.
• Add ArgumentStack#asImmutableCopy() for gaining independent copies.

ArgumentStack fixes, Sponge update

• Fixed some ArgumentStack#of() methods not respecting quotes and joining strings into one.
• Added ArgumentStack#empty()
• Fixed Sponge implementation
• Allow response types of java.util.Optional
• Optimize CommandPath#getCategoryPath()
• Pass ArgumentStack#asImmutableView() to command conditions
• more fixes

Full Changelog: 1.2...1.3

Exceptions and actors update

Changelog:

• Replaced inaccurate chat colorizing
• Added XYZCommandActor#wrap(...) methods
• Exposed CommandActor to CommandExceptionHandler#handleException
• Removed #getActor() from exceptions
• Added support for Sponge's TextMessageException.
• Created a default exception handler for Velocity
• SendableExceptions no longer require a CommandActor to be supplied.

Initial release

1.0

Push gradle wrapper files