Optimize MODLOAD (removed WATCHLOAD) and Add CACHELOAD.

[Katsute]

Prerequisites

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• My code follows the style listed in CONTRIBUTING.
• I have checked that no other similar pull requests already exists.
• Build compiles.
• Build runs without exceptions.
• I have added/modified documentation (if applicable).
• I have added/modified test cases.

Changes Made

List changes made and/or relevant issues. Please keep changed in reverse chronological order (newest at top).

• Replace WATCHLOAD with MODLOAD (more efficient) (ClosesReplace WatchLoad #106)
• Add CACHELOAD (ClosesImplement caching system #80)

[Katsute]

Todo: Add one more additional test to make sure that updating a cached file doesn't update a irrelevant cached file.

[Katsute]

CacheAdapter should keep a variable for the closest expiry, then use this to determine when to check all files to clear and set the closest expiry from this.