* expose Spectrahedron interface to R

- create class spectrahedron
- expose function to write sdpa format files in R

* expose read_sdpa function to R and documentation

* R documentation and examples

- fix examples
- add data for example
- add roxygen comments

* tests for sdpa format manager

- add copyrights headers
- add test that writes and reads a sdpa format file
- add the test in test/CMakeLists.txt

* add example code for sdpa files

- create folder examples in root
- add an example main to read / write sdpa format files

* fix file format

* fix file encoding

* use soft wrap with lines

* create folder spectrahedra

- move in new folder spectrahedron.h, LMI.h
- update CMakeLists.txt in folder examples, tests
- update Makevars in R-prog/src and in cran_gen
- add documentation for sdpa file example

* examples/spectrahedra documentation

* examples/spectrahedra documentation

fix headers

* rename R modules

- rename module in polytopes_modules.cpp to "polytopes"
- rename module in spectrahedron_module.cpp to "spectrahedron"
- fix dates in copyrights headers in files
- add a newline in end of file spectrahedron.h

* make LMI::getMatrices() return std::vector const &

Also fix parameters documentation in R for functions

- readSDPAFormatFile
- loadSDPAFormatFile
- writeSDPAFormatFile

* rename typedefs in spectrahedron.cpp

- rename SPECTRAHEDRON typedef to Spectrahedron
- remove unneeded class _Spectrahedron in spectrahedron.cpp

* SDP Solver

Simulated annealing for spectrahedra

- add libraries spectra, arpack
- add random walks Hamiltonian monte carlo with reflections under Boltzmann distribution and coordinate Hit and Run
- in folder matrices there are the classes solving the required eigenvalue problems

* fix test/SDP/CMakeLists.txt to include dependencies

* fix test/SDP/CMakeLists.txt fix libgfortran

* refactor

- rename folder matrices to matrix_operations
- refactor boltzmann_hmc_walk.hpp to follow the style of the rest random walks
- in boost_random_number_generator.hpp create a default (empty) constructor

* add example boltzmannHmcWalk.cpp

- update examples/spectrahedron/README.md
- remove files CoordinateDirectionsHitAndRun_RandomWalk.h and optimization/SDPA-FormatManager.h (duplicate)

* fix type

* add examples/spectrahedra/semidefiniteProgramming.cpp

- fix bug in SimulatedAnnealing.h (minor - missed from previous refactor)
- update examples/spectrahedra/readme.md
- EigenvaluesProblems.h when calling arpack method findEigenvalues()
  make sure ncv <= number of rows of matrix

* refactor

- rename files to match package
- in the simulated_annealing.hpp destroy the class and expose the functionality as free functions
- update examples and README.md

* add tests

Add tests in folder tests/SDP to test the sdp solver and the boundary oracles.They have their own CMakeLists.txt

* fix README.mde

compilation instructions

* fix README.md

* fix include

* fix errors from previous merge

Accept everything as was in upstream/develop

* newline in end of file

* remove wrong #include

causes error with R interface

* add #include

required by spectrahedron.h

* add \dontrun{} in R example

* try fix in cmakefiles

* Create testSDP.yml

* try fix in cmakefiles

* try fix in cmakefiles

* try fix in cmakefiles

* fix CMakeLists.txt and readne.md

* fix cmakelists (#2)

Co-authored-by: Tolis Chalkis <tolis.chal@gmail.com>