Feedback on the performance tab

[phyrophone]

just some minor nitpicks and ideas.

regarding context menus:

• can't copy some graphs (memory, disk, nic, gpu)
• change units option only available in nic
• graph time/refresh interval/about tux manager options only available on the small previews on the left
• maybe rephrase copy to copy graph, to inform the user that they can copy an image and not just some random text
• maybe add option to copy all stats instead of a single number
• maybe add percentage tooltip for the memory composition thing
• the tooltip when hovering over a graph doesn't update unless moved right/left

inconsistent font/sizes/colors/placement for text:

• the title GPU 0 is black and not blue fixed
• model name is under the title for cpu but above the percentage text for other tabs
• wrong font/color/size/thickness for smaller text under swap vs all other tabs fixed
• wrong color for text under gpu vs all other tabs
• Missing X % text in the upper right corner for the memory tab
• X Kb/s above the nic graph should be aligned to the top of the graph, instead of being at the same height as the title. Like the 0 below the graph. fixed

other stuff:

• display percentages in the stats sections. e.g:

In use: X GB (Y%)                        Available: X GB
Dirty: X GB (Y%)                          Free: X GB(Y%)

[phyrophone]

text related prs: #47 #48

[benapetr]

This fixes your graph copy issues

3c94098