new PH vs DAC functionalities

Hi everybody, 
    I created two new commands to do PH vs DAC scan. They are simply an upgrade of the existing commands 'shmoo' and 'phscan'.
-  'phscandac' : to do a PH scan vs one DAC with the possibility of pixel, dac and dacrange selection.
The output is not in the log file but it is a pop-up windows as for 'phscan'. You can not interact with that but anyhow I think it can be very useful to do a quick check of the dacs.
- 'dacdac' : you can do a PH scan vs 2 DACs with the selection of pixel, DACs and dac range. the output is in the log file with the 'psi46test style'.

I tried to make them robust and I added some error messages and checks.
I tested them with a single ROC and DTB 2.1 SW 1.17 FW 1.10.
IMPORTANT: to use them you have to run 'startroc' before.

In addition to this, I changed also the default values of some DACs in testdig.cpp in order to make them equal to the one present in the script 'startroc'.
In particular I think that Vcal=2 was a little bit 'dengerous' as default value.

I hope that it can be useful.
Cheers,
martino