Issue for particles in quad cell

Due to a high convergence value (1.0e-2) in phy2logQuad (variable conv),
    particles were being stuck in some elements, reaching a segmentation
    fault. The new limit (1.0e-4) should avoid this.

src/modules/mesh/2DCyl/moduleMesh2DCyl.f90

@@ -524,7 +524,7 @@ MODULE moduleMesh2DCyl
       conv = 1.D0
       XiO  = 0.D0
 
-      DO WHILE(conv > 1.D-2)
+      DO WHILE(conv > 1.D-4)
         dPsi = self%dPsi(XiO, 4)
         pDer = self%partialDer(4, dPsi)
         detJ = self%detJac(pDer)

src/modules/mesh/moduleMesh.f90

@@ -639,8 +639,8 @@ MODULE moduleMesh
       CLASS(meshCell), INTENT(inout):: self
       CLASS(particle), INTENT(inout), TARGET:: part
       CLASS(meshCell), OPTIONAL, INTENT(in):: oldCell
-      REAL(8):: Xi(1:3)
-      CLASS(meshElement), POINTER:: neighbourElement
+      REAL(8):: Xi(1:3) = 0.D0
+      CLASS(meshElement), POINTER:: neighbourElement => NULL()
       INTEGER:: sp
 
       Xi = self%phy2log(part%r)