This searches for the given model name in a directory
getModel( name = defaultModel(), dir = system.file(package = pkg, "models"), pkg = "tdmore" )
| name | model name (filename without `.r`)  | 
    
|---|---|
| dir | model directory; uses the package `models` directory by default  | 
    
| pkg | the package in which to search for a `models` directory  | 
    
a tdmore model object