Normalise icons present in blocks (All but standard theme)

Follows changes in MDL-36323.

This issue has been raised to make sure that the changed in the blocks CSS do not affect or break the themes (except the 'standard' one).
If they're broken, this issue should fix the problems.

You want to look at:

• the block edit icons
• the docked block edit icons
• the navigation block
• the settings block
• some padding between icons and text in blocks such as activities, courses, etc...