TODO-List:
===============

* check the whole code for memory leaks

* check the whole code for verbose messages

* add example/test directory
    * simulation with hierarchical schematics and libs
    * simulations with subcircuits

* the whole variable structs are crap. The next redesign should use 
  key-value lists. (slower but much easier to maintain)

* buffer needs to be UTF-8: conversion required

* if parametric simulation is activ, something went wrong
  (can't reproduce this at the moment)

* run simulations in background and add a kill button 
  beside the simulation buttons (stop sign)

* run all external commands inside threads

* remove the requirement of a terminal for easyspice,
  running ngspice in a shell is ok.

* make dist: learn how to include the tests files

* option menu: maybe add an spice options menu, there's allready a dialog
  inside interface.c (never seen before)

* remove global EasySpice struct

