Mode bar icon set feedback

This is a list of features of the icon set introduced with b599edb9b7e for easier double checking they are intentional (add an explanation why the change is wanted, and mark with ), or accidental (mark , and link corrective change on gerrit, once change is integrated, mark with ).

• The Build icon is no more recognizable as hammer - this looks like two toy bricks
• The two parts of the Build mode icon are disconnected, making the hammer they are supposed to signify look broken, unusable for building something.

• The Build Hammer and is outlined/standalone, Wrench is solid/circled
• The slope of the Build hammer shaft is different from the slope of the Wrench handle, making the suite look inconsistent.

• The circle around the Project wrench and question mark does not have any meaning for me.

• The bug overlay on the debug run button is barely recognizable for me.

• The bug is now inconsistent with the favicon of bugreports.qt.io: https://bugreports.qt.io/favicon.png

• Both "Run" and "Start debugging" icons are nearly the same, the "bug" on the second one is nearly invisible, looks like some gray smudge. The empty triangles for both of them have very thin borders, making them hardly visible. Currently, when I want to click "Run", my brain tells me: "count the 3rd icon from the bottom and click there".

• It looks like the design and debug icons are 1 or two "pixels" smaller than the rest, and the projects and the help icons looks smaller because of the circle (which makes the icon within the circle smaller than the other icons)

• The Run and Debugger start and pause icons are now inconsistent with their cousins in the debugger toolbar, analyzer toolbar and  the QML preview starter
• The Stop overlay of the Run, Debug and Build icons is still solid red, not matching the outlined style of the side bar. /if/ made outlined, it will be inconsistent with its cousins in the debugger and analyzer toolbar.