better indicator icons

• use own icons for indicator sections
• in MODE_ALL use unicode symbols that resemble the indicator icons

Inital Release

The initial release includes a basic extension that runs an intel_gpu_top process to collect GPU stats.

Features

• pipe GPU stats to the indicator
• supported stats: Power Usage, Render Load, and VA Load

Limitations

• extension assumes you have only one GPU and will pick the first it finds
• extension assumes intel_gpu_top will also pick the first GPU and that all its output is for this GPU
• only tested on one Intel Laptop (X1 Carbon G6)