stweaks: clean-up and organization
Tabs are now ordered as:

[CPU] [GPU] [SCREEN] [SOUND] [BLN] [MEMORY] [FILE SYSTEM] [TWEAKS] [MISC]

This way most important hardware tunables are ordered first (cpu/gpu)

Also merged cpu voltage tab with cpu tab, and i/o scheduler to file system tab

Signed-off-by: Gustavo Santos <gustavo.santos0106@gmail.com>