[Description]
- Docker infrastructure for the project;
- Compilation script;
- Build project against C++17 standart;

missing)
Change number of nodes in TrapezoidalIntegration1D from 50 to 40 (for
compatibility with other integration routines)

Implement version information

See merge request !1

module naming #24
(modification agreed with Herve during his stay in Warsaw)

characters (and not cast from integer) #24

rule probing function in equidistant steps between ln(a) and ln(b) 

- Add layout scheme to match PARTONS 
- Apply current style
- Update doxyfile
   - update titles
   - update mathjax script
   - make it similar to PARTONS doxyfile

- Generate tag file to be used by PARTONS documentation.

- Add missing build/ folder.
- Add .gitignore.
- Fix FindElementaryUtils.cmake.

In ALL (trunk):
- Improvements on the previous cmake commits.

In Elementary_utils (trunk):
- Add the installation routines in CMakeLists.
- Add doxyfile.

In NumA++ (trunk):
- Add the installation routines in CMakeLists.
- Add FindElementaryUtils.cmake module and adapt CMakeLists.

In NumA++_Tests (trunk):
- Add FindElementaryUtils.cmake & FindNumA++.cmake modules and adapt CMakeLists.

In PARTONS (trunk):
- Add the installation routines in CMakeLists.
- Add FindElementaryUtils.cmake & FindNumA++.cmake modules and adapt CMakeLists.

In PARTONS_exe, PARTONS_release, PARTONS_Tests, PARTONS_Fits (trunk):
- Add FindElementaryUtils.cmake, FindNumA++.cmake & FindPARTONS.cmake modules and adapt CMakeLists.

Adding simple cubic spline algorithm for NumA++

In NumA++:
- Correct the default absolute tolerance to 1e-3 in Integrator1D, instead of 0.

In NumA++:
- Correct the warning in DExp.

In NumA++:
- Initialize Eigen vectors to zero in LSMRSolver, to avoid random results (and maybe nan).

In PARTONS_Fits:
- Propagate changes in parameters names for DVCSConstantCFFModel.

In NumA++ (trunk):
- Removed the function solveLSMR in LinAlgUtils.
- New class LSMRSolver (using Eigen vectors and matrices for the computation).
- Removed old LSMR classes.
- Various conversions of stringstream to Formatter and runtime_error to CustomException.

In NumA++_Test (trunk):
- Propagation.