ANSI colour support and terminal detection

Provides POSIX/UNIX counterpart for Windows colours implementation using ANSI escape codes. It also detects if stdout is a tty and disables colours when using pipes or file output.

include/internal/catch_console_colour_impl.hpp

@@ -83,11 +83,48 @@ namespace Catch {
 
 #else
 
+#include <unistd.h>
+
 namespace Catch {
-    TextColour::TextColour( Colours ){}
-    TextColour::~TextColour(){}
-    void TextColour::set( Colours ){}
-    
+
+    TextColour::TextColour( Colours colour ) {
+        if( colour )
+            set( colour );
+    }
+
+    TextColour::~TextColour() {
+        set( TextColour::None );
+    }
+
+    void TextColour::set( Colours colour ) {
+        if( isatty( fileno(stdout) ) )
+        switch( colour ) {
+            case TextColour::FileName:
+                std::cout << "\e[1m";    // bold
+                break;
+            case TextColour::ResultError:
+                std::cout << "\e[1;31m"; // bright red
+                break;
+            case TextColour::ResultSuccess:
+                std::cout << "\e[1;32m"; // bright green
+                break;
+            case TextColour::Error:
+                std::cout << "\e[0;31m"; // dark red
+                break;
+            case TextColour::Success:
+                std::cout << "\e[0;32m"; // dark green
+                break;
+            case TextColour::OriginalExpression:
+                std::cout << "\e[0;36m"; // cyan
+                break;
+            case TextColour::ReconstructedExpression:
+                std::cout << "\e[0;33m"; // yellow
+                break;
+            default:
+                std::cout << "\e[0m"; // reset
+        }
+    }
+
 } // end namespace Catch
 
 #endif