Improve pool memory management

[attackgoat]

The pool types have the ability to grow and eventually use up all available resources.

This can be reproduced using the MSAA example or any other code which leases resources dependent on the swapchain size and then continuously resizing the window in order to generate many requests for resources with different sizes.

This is related to but not necessarily the entire fix for #69.

Additionally, there should be a new pool type which focuses on using the least possible memory overall.

• Review and improve existing Pool code
• Add basic memory management functions
• Add new FifoPool implementation
• Add bucket size configuration to all pool types
• Ensure documentation and relevant examples are in place