added various keywords to calculator

Added functions I commonly use on e.g. google calculator but were missed by parser.

Specifically I added:
e (constant like pi)
tan, arcsin, and arctan
log and ln

Plugins/Wox.Plugin.Calculator/Main.cs

@@ -10,7 +10,8 @@ namespace Wox.Plugin.Caculator
     {
         private static Regex regValidExpressChar = new Regex(
                         @"^(" +
-                        @"sin|cos|ceil|floor|exp|pi|max|min|det|arccos|abs|" +
+                        @"ceil|floor|exp|pi|e|max|min|det|abs|log|ln" +
+                        @"sin|cos|tan|arcsin|arccos|arctan|" +
                         @"eigval|eigvec|eig|sum|polar|plot|round|sort|real|zeta|" +
                         @"bin2dec|hex2dec|oct2dec|" +
                         @"==|~=|&&|\|\||" +