Dexed debugger UI now supports inspection of the variables based on mouse motion

[Basile B.]

I don't know why I havent implemented this earlier as it was 
quite simple. It's basically the same as when you evaluate a 
custom expression excepted that you use the mouse position to 
extract a (more or less, TBH) precise unary expression.

     https://imgur.com/a/e4urRY9

Only problem is that GDB requires explicit dereferences, that are 
normally automatic in D semantic, so big chain of identifiers 
wont work and display '???'.

Example:

     for D       :    a.d.c.somevar
     GDB needs   :  (*a).(*d).(*c).somevar

if a,d and c are classes or struct pointers. So far dexed will 
display

______________________________________
exp: a.d.c.somevar
---
(result of -data-evaluate $exp)
---
(result of -data-evaluate *$exp)
______________________________________

so only one dereference. And in the a.d.c.somevar example this 
would not work.