ENH: Replace use of IsADirName and IsAFileName methods of otbSystem.h by similar ones of itksys/SystemTools.hxx

ENH: Added GetInput() methods to QtWidgetFooParameter classes; Set non-initializerd pointers to NULL on constructor header.

ENH: Replace use of SetToLower and SetToUpper methods of otbSystem.h by similar ones of itksys/SystemTools.hxx

ENH: Replace use of GetPathName, GetShortFileName and GetExtension methods of otbSystem.h by similar ones of itksys/SystemTools.hxx

I noticed this issue when I installed cuda which depends on gold kinker on
ubuntu 12.04:

http://doc.ubuntu-fr.org/cuda#pre-requis

I achieve in compiling external project to OTb with this linker by adding
explicit link to dl libs in otbossim library.

I did not dig too much into this problem but it may be related to modification
in DSO linking documented here:

https://wiki.debian.org/ToolChain/DSOLinking#Onlylinkwithneededlibraries

OTB does not support anymore classes which use liblas in version 4.0:

-otbPointSetFileReader

You can still access to these classes, related tests and examples in OTB 3.20.

BUG: Duplicating bugfix 5a1f22670151 into a 3.20.0 based branch for bugfix sharing with 3.20.0 users

CommandLine Launcher enables all parameter which it parses and
is outxml check for Enabled parameter while SetParameter* used
by Wrappers doesn't Enable the parameter.

OTB does not support anymore classes which use pqxx in version 4.0:

Classes removed in OTBv4 are:
        - PostGISConnectionImplementation
        - PostGISTable
        - GISTableFunction
        - PostGISCreateTableTransactor
        - PostGISFromStringTransactor
        - PostGISQueryTransactor
        - TransactorGISTableFunction

You can still access to these classes, related tests and examples in OTB 3.20.