Bump library version to 1.7.5

Fix race condition NPE in init methods

Switch from Javaparser to Javapoet for code generation

Update Version

Improve startup time with removing static constructor in EmojiManager…

… and pre-computing variables where possible

Add missing parameter Javadoc

Sort map entries alphabetically

Fix Unicode not correctly being generated for Java classes

Fix mixed up GitHub and slack aliases when generating static Java code

Add EmojiLoader methods to readme