GitLab

The tree structure can now be printed to the WaveFront OBJ format. The
3D object generated is draws the tree leaves.

Two stream modifiers are added to choose the format:
 - scalfmm::fmt::term outputs the tree in terminal format
 - scalfmm::fmt::obj outputs the tree in obj format

Index the custom particle ontainer to allow easier testing.

Make node data inherit FBasicCell to work with standard algorithms.

Add operator call counts.

Add a partial P2P to work with OpenMP 4 task adaptive algorithm.

Add more precise information per descriptor through the optional `info`
static method. The adaptive tree descriptor gives information about the
options.

Remove old help message hints that aren't relevant anymore.

Rename DescriptorLookup.hpp to TestDriver.hpp

Allow tree descriptor to adapt to kernel descriptor: the node data and
particle containers are now retrieved from the kernel descriptor type
definitions.

Add some comments.

Add FCountKernel descriptor.

An allocation was made for each child. Now an array of children is
allocated in one go.

Those fixes are needed when FTic does not rely on OpenMP timer.

Conflicts:
	UTests/CMakeLists.txt

cmake Finds: improve the way library dirs are added in blas/lapack, remove blas lib to search in essl

The adaptive algorithm have been updated to use them.

Add a peek method to check timer without stopping it
Make tac return elapsed time
Add c++11 std::chrono timing

The methods `name` and `description` are implemented.

The timers are mapped to a std::string. The basic ones (P2L, P2M, M2M,
M2P, M2L, L2L, L2P, P2P) have a constexpr definition. Any new timer can
be added by calling `Timers["timer name"];`.