Update api.php

Changes to how achievements were processed, both functions for obtaining achievement results will generate a correct object of data.

"parseAchievements(id)" will parse all achievements for a specific character id, it will go through all categories, parse, and append onto a main achievement object. The $API->getAchievements() will contain an object with the entire achievements parsed results.

"parseAchievementsByCategory(category, id)" will parse achievements for a specific category and a specific character id. The $API->getAchievements() will be an array containing the category ID and its achievement object result.

Additional API Methods have been added such as:
- getTotalPoints
- getCurrentPoints
- getPointsPercentage
- getTotalAchievements
- getCurrentAchievements