Implementation of 0D grid for analysis of collisional operators.

Still need to add a 0D pusher and the corresponding input configuration
and documentation.

src/modules/mesh/inout/0D/moduleMeshInput0D.f90

@@ -0,0 +1,66 @@
+MODULE moduleMeshInput0D
+  !Creates a 0D mesh. mostly used for testing collisional processes.
+  !This mesh consists on 1 node and 1 volume in which all particles are located.
+  !No boundary conditions and no pusher should be applied to this geometry.
+  !Output should go to a single file (per species) in which each row represents an iteration.
+  !In principle, no EM field is applied.
+
+  CONTAINS
+    !Inits the 0D mesh
+    SUBROUTINE init0D(self)
+      USE moduleMesh
+      USE moduleMeshOutput0D
+      IMPLICIT NONE
+
+      CLASS(meshGeneric), INTENT(inout), TARGET:: self
+
+        IF (ASSOCIATED(meshForMCC, self)) self%printColl => printColl0D
+        SELECT TYPE(self)
+        TYPE IS(meshParticles)
+          self%printOutput => printOutput0D
+          self%printEM     => printEM0D
+
+        END SELECT
+        self%readMesh => read0D
+
+    END SUBROUTINE init0D
+
+    !Reads a 0D mesh file.
+    !No reading is actually done as the 0D mesh is a fixed one
+    SUBROUTINE read0D(self, filename)
+      USE moduleMesh
+      USE moduleMesh0D
+      IMPLICIT NONE
+
+      CLASS(meshGeneric), INTENT(inout):: self
+      CHARACTER(:), ALLOCATABLE, INTENT(in):: filename !Dummy file, not used
+      REAL(8):: r(1:3)
+
+      !Allocates one node
+      self%numNodes = 1
+      ALLOCATE(self%nodes(1:1))
+      !Allocates one volume
+      self%numVols = 1
+      ALLOCATE(self%vols(1:1))
+      !Allocates matrix K
+      SELECT TYPE(self)
+      TYPE IS(meshParticles)
+        ALLOCATE(self%K(1:1, 1:1))
+        ALLOCATE(self%IPIV(1:1, 1:1))
+        self%K = 0.D0
+        self%IPIV = 0.D0
+
+      END SELECT
+
+      !Creates the node
+      ALLOCATE(meshNode0D:: self%nodes(1)%obj)
+      r = 0.D0
+      CALL self%nodes(1)%obj%init(1, r)
+
+      !Creates the volume
+      ALLOCATE(meshVol0D:: self%vols(1)%obj)
+      CALL self%vols(1)%obj%init(1, (/ 1/), self%nodes)
+
+    END SUBROUTINE read0D
+
+END MODULE moduleMeshInput0D