Option and key ("*") to collapse / expand all branches under PID 1

(and PID 2 if kernel threads are shown)

Based on hishamhm/htop#510 by Krishna Chaitanya, B
Closes #68

Settings.h

@@ -47,6 +47,7 @@ typedef struct Settings_ {
    #endif
    bool treeView;
    bool treeViewAlwaysByPID;
+   bool allBranchesCollapsed;
    bool showProgramPath;
    bool shadowOtherUsers;
    bool showThreadNames;