Merge branch 'terencehill/modified_default_cvars' into 'master'

Fix for menu modifying default cvar values (float numbers)

Remove trailing 0s before saving float numbers into cvars in the menu.  Reason: with a fresh config a few cvars were considered modified because on menu start sliders rewrite the current cvar values adding trailing 0s

These are the cvars that were added in config.cfg on menu start after having pressed save setting in the first run dialog:
```
seta "crosshair_alpha" "0.800000"
seta "crosshair_dot_size" "0.600000"
seta "crosshair_ring_alpha" "0.200000"
"crosshair_size" "0.400000"
seta "hud_panel_centerprint_fade_out" "0.500000"
```

See merge request !299

diff --cc defaultXonotic.cfg
Simple merge

diff --cc qcsrc/common/util.qh
Simple merge