[Matlab/Samples] Fix broken default argument checks

There are no classes named 'GasMix' or (lowercase) 'solution', so these checks
would always fail and the input argument would always be silently ignored.

samples/matlab/equil.m

@@ -6,7 +6,7 @@ function equil(g)
 %    equivalence ratio.
 help equil;
 
-if nargin == 1 & isa(g,'GasMix')
+if nargin == 1
    gas = g;
 else
    gas = IdealGasMix('gri30.cti');

samples/matlab/ignite.m

@@ -8,7 +8,7 @@ function plotdata = ignite(g)
 
 help ignite
 
-if nargin == 1 & isa(g,'solution')
+if nargin == 1
    gas = g;
 else
    gas = IdealGasMix('gri30.xml');

samples/matlab/ignite_hp.m

@@ -5,7 +5,7 @@ function ignite_hp(gas)
 
 help ignite_hp
 
-if nargin == 0 | ~isa(gas,'GasMix')
+if nargin == 0
    gas = IdealGasMix('gri30.xml');
 end
 

samples/matlab/ignite_uv.m

@@ -4,7 +4,7 @@ function ignite_uv(gas)
 %
 help ignite_uv
 
-if nargin == 0 | ~isa(gas,'GasMix')
+if nargin == 0
    gas = IdealGasMix('gri30.xml');
 end
 

samples/matlab/isentropic.m

@@ -6,7 +6,7 @@ function isentropic(g)
 %
 help isentropic
 
-if nargin == 1 & isa(g,'solution')
+if nargin == 1
    gas = g;
 else
    gas = IdealGasMix('gri30.xml');

samples/matlab/prandtl1.m

@@ -7,7 +7,7 @@ function prandtl1(g)
 %
 help prandtl1
 
-if nargin == 1 & isa(g,'solution')
+if nargin == 1
    gas = g;
 else
    gas = GRI30('Mix');

samples/matlab/prandtl2.m

@@ -6,7 +6,7 @@ function prandtl2(g)
 %
 help prandtl2
 
-if nargin == 1 & isa(g,'solution')
+if nargin == 1
    gas = g;
 else
    gas = GRI30('Multi');

samples/matlab/reactor1.m

@@ -12,7 +12,7 @@ function reactor1(g)
 
 help reactor1
 
-if nargin == 1 & isa(g,'solution')
+if nargin == 1
    gas = g;
 else
    gas = GRI30;

samples/matlab/reactor2.m

@@ -8,7 +8,7 @@ function reactor2(g)
 
 help reactor2
 
-if nargin == 1 & isa(g,'solution')
+if nargin == 1
    gas = g;
 else
    gas = GRI30;

samples/matlab/transport1.m

@@ -3,7 +3,7 @@ function transport1(g)
 %
 help transport1
 
-if nargin == 1 & isa(g,'GasMix')
+if nargin == 1
    gas = g;
 else
    gas = GRI30('Mix');