ENH: adjustments to Switch
- align Switch more with Enum. Now have find(), found() static methods. Constructors with failsafe option. The find() method makes for clearer coding: OLD Switch sw(some_string, true); // NB: true = allowBad if (sw.valid()) ... NOW Switch sw = Switch::find(some_string); if (sw.good()) ... or if (Switch::found(some_string)) ... - improve construct from dictionary to handle all valid token types. Previously just read in a word. - Remove asText() method - replaced by c_str() and str() several versions ago.