[New app] setStockColGUI

[lmsimp]

No description provided.

[lgatto]

setStockColsGUI <- function(fcol, cols) { ... }
## `cols` is an optional arguments to set starting colours in the GUI 
## `fcol` marker feature variable (could be a vector or matrix)
## 
## The app would enable users to choose colours for their markers, 
## making sure that the order will match when calling `plot2D`. Before 
## exit, the app would run `setStockcol(x)`, where `x` is the user-defined 
## vector of colours, and `return(x)`.