derelict-gl3 + derelict-glfw3 + derelict-util (version?) - need instructions on handling basic package version dependency conflicts

[Daniel]

When trying all 3 of these libraries together (just adding them 
with e.g. `derelict-gl3` so latest version) I get:

```
C:\Users\fruit\OneDrive\Desktop\MathProjects\DerelictTest\derelicttest2>dub generate visuald
Error Unresolvable dependencies to package derelict-util:
   derelict-gl3 1.0.24 depends on derelict-util >=1.0.3
   derelict-glfw3 3.1.3 depends on derelict-util ~>2.0.4
   derelicttest2 ~master depends on derelict-util ~>2.1.0
```

Not sure what it means, or how to fix without spending too much 
time trying out all the 1000's of possible combinations of 
package versions.

So any hints?