Optimize and clean up SVG icons

[valtlai]

• Remove xlink namespace when not used
• Remove svg[version] attribute
• Remove px from pixel units
• Remove unused ids
• Remove useless groups
• Optimize path data (2 decimal places)
• Remove ry when same as rx (ry defaults to rx)
• For consistency: lowercase hex colors, attributes order, indentation to 4 spaces

[petetnt]

NEAT! No visible changes according to riff diff, LGTM

[ficristo]

@valtlait Did you use some tools or have you done it manually?

[valtlai]

@ficristo It’s done manually, expect path optimization which is done using some regexes.

[ficristo]

@valtlait Thank you for the answer.

[abose]

Thanks @valtlait .
Have to verify this in hidpi displays before merging. Will merge tomorrow after checking out.

[abose]

Verified on HiDpi displays. LGTM
Merging.
Thanks @valtlait