First commit of code.

New functionality:
- DSMC module:
  - 2D cyl geometry
    - GMSH file format
    - Elastic cross-section for Argon-Argon collisions.
    - Basic boundary conditions: reflection, absorption and axis
      symmetry.

Bugs fixed:

Other comments:
- Still searching for name.

src/modules/moduleSpecies.f95

@@ -0,0 +1,66 @@
+!Contains the information about species (particles)
+MODULE moduleSpecies
+  USE moduleCaseParam
+  USE moduleList
+  IMPLICIT NONE
+  
+  TYPE, ABSTRACT:: speciesGeneric
+    CHARACTER(:), ALLOCATABLE:: name
+    REAL(8):: m=0.D0, weight=0.D0
+    INTEGER:: pt=0
+  END TYPE speciesGeneric
+
+  TYPE, EXTENDS(speciesGeneric):: speciesNeutral
+
+  END TYPE speciesNeutral
+
+  TYPE, EXTENDS(speciesGeneric):: speciesCharged
+    REAL(8):: q=0.D0, qm=0.D0
+
+  END TYPE speciesCharged
+
+  TYPE:: speciesCont
+    CLASS(speciesGeneric), ALLOCATABLE:: obj
+
+  END TYPE
+
+  INTEGER:: nSpecies
+  TYPE(speciesCont), ALLOCATABLE:: species(:)
+
+  TYPE particle
+    REAL(8):: r(1:3) !Position
+    REAL(8):: v(1:3) !Velocity
+    INTEGER:: pt !Particle species id
+    INTEGER:: e_p !Index of element in which the particle is located
+    REAL(8):: xLog(1:2) !Logical coordinates of particle in element e_p.
+    LOGICAL:: n_in !Flag that indicates if a particle is in the domain
+
+  END TYPE particle
+
+  INTEGER:: n_part_old, n_part_new
+  INTEGER:: nPartInj
+  !Arrays that define the particles
+  TYPE(particle), ALLOCATABLE, DIMENSION(:), TARGET:: part_old
+  TYPE(particle), ALLOCATABLE, DIMENSION(:):: part_new
+  TYPE(particle), ALLOCATABLE, DIMENSION(:):: part_inj !array of inject particles
+
+  CONTAINS
+    FUNCTION speciesName2Index(speciesName) RESULT(pt)
+      IMPLICIT NONE
+
+      CHARACTER(:), ALLOCATABLE:: speciesName
+      INTEGER:: pt 
+      INTEGER:: n
+
+      pt = 0
+      DO n = 1, nSpecies
+        IF (speciesName == species(n)%obj%name) THEN
+          pt = species(n)%obj%pt
+          EXIT
+        END IF
+      END DO
+      !TODO: add error handling when species not found
+
+    END FUNCTION speciesName2Index
+
+END MODULE moduleSpecies