ENH: Document that conversion applications in otb don't support complex pixel types as output

See merge request !153

ENH: Allow to compute modulus and phase from 2 bands scalar image

See merge request !154

BUG fix issue 1656 related to eratic behavior of cmake configuration

Closes #1656

See merge request !156

rename files with txx extension to hxx

See merge request !152

For now complex pixel types are not supported by Convert and DynamicConvert
applications (see switch/case in the generic DoExecute method). This commit just
document this limitation.

Note that the ExtractROI application can be used to convert image from/to
complex image.

The support of complex images in otb applications as improved in version
6.6. There is generic mechanism based on teh ClampImageFilter which allow to
go from/to complex or multi-bands scalar images.

The only change is to read the input image as ComplexFloatImageType which
support both complex image (single band) or image with 2 bands which corresponds
to the real and imaginary parts.

The documentation of the application has been updated to reflect this
modification.

BUG: fix issue #1639 Update UserValue flag in QtWidgetParameterList

Closes #1639

See merge request !142

OTB followed since the beginning the ITK convention and use .txx extension for all
template classes. Nevertheless, some development tools do not recognize .txx
file extension. Other tool like GitHub can't do in-browser syntax highlighting for
txx files I think.

The root problem is the use of the txx which should be changed to hxx (or hpp).

In 2011, after an in-depth discussion near April 20, 2011 on the
Insight-Developers mailing list, ITK rename all txx files to hxx (and event
prevent the push of .txx files with a pre-commit hook). It happens is major release v4.

You can find some arguments in the discussion about the change and also in other
projects related to ITK which applied the same modification, see for instance VXL:

https://github.com/vxl/vxl/issues/209

This commit apply now the same modification for OTB.

I understand that it will change some habit for developers and don't bring new
features but I think that in general it is better to stay align with ITK guidelines.

In my opinion, it always facilitate the use of OTB and ITK together if we share
when we can the same code architecture, directory organization, naming
conventions...

ENH: display parameter description as tool tip for the QtWidgetBoolParameter

See merge request !149

Resolve "Warn otbcli user about unused parameters"

See merge request !144

REFAC: include-what-you-use in Modules/Core/

See merge request !138

DOC: Minor fixes in Software Guide

See merge request !140

BUG: fix issue !1639 Update UserValue flag when a parameter is modified in QtWidgetParameterList widget

The QtWidgetParameterList widget should signal that an input parameter as been
modify by the user.Then, it set the UserValue flag from the corresponding parameter to
True.
It was spotted as the UserValue flag is used by the ParseApplication method used
to list parameter modified by the user in the GUI which is used to build the
corresponding command-line from the application GUI (displayed in the Log tab).

COMP: fix gcc 7 'defined' warnings

See merge request !127

DOC: Set of proposed edits to the documentation

See merge request orfeotoolbox/otb!137