misccoms.c: add more deleting function in 'quit' for shared ngspice
sharedspice.c: improve progress analysis
dctran.c, runcoms2.c: shared ngspice: remove plot data upon 'bg_halt' and 'remcirc'
inp.c: comments added
inperrc.c: comments added, white spaces
allow cshell variablen substitution with and without $&var
cleanup some compiler warnings
com_psd: reuse the window function fft_windows
inpcom.c: update some comments
inpcom.c: debug printout to debug-out.txt improved