Add period to the ends of usage string sentences.

The English, she is hard on me.

Author: rocky

mathics/autoload/settings.m

@@ -2,11 +2,11 @@
 (* Settings for Mathics Core *)
 (*****************************)
 
-Settings`$TraceGet::usage = "If this Boolean variable is set True, 'Get' traces the lines it reads that start a new expression";
+Settings`$TraceGet::usage = "If this Boolean variable is set True, 'Get' traces the lines it reads that start a new expression.";
 Settings`$TraceGet = False
 Unprotect[Settings`$TraceGet]
 
 
-Settings`$PreferredBackendMethod::usage = "Set this do whether to use mpmath, numpy or Sympy for numeric and symbolic constants and methods when there is a choice";
+Settings`$PreferredBackendMethod::usage = "This sets whether to use mpmath, numpy or Sympy for numeric and symbolic constants and methods, when there is a choice.";
 Settings`$PreferredBackendMethod = "sympy"
 Unprotect[Settings`$PreferredBackendMethod]