Update parset (nicer test case)

src/one-body-sample.parset

@@ -3,13 +3,13 @@ timesteps = 100
 
 verbose = false
 
-useNonlinearGS = true
+useNonlinearGS = false # true
 useGS = false
 useTruncatedGS = false
 useTNNMG = true
 
 [grid]
-refinements = 5
+refinements = 3
 
 [body]
 E = 3e2
@@ -20,7 +20,7 @@ nu = 0.3
 
 [solver]
 maxiterations = 1000000
-tolerance = 1e-8
+tolerance = 1e-12
 
 [localsolver]
 steps = 1