Add common virtualenv segment

powerline/config_files/colorschemes/shell/default.json

@@ -1,5 +1,5 @@
 {
-	"name": "Default color scheme for terminal prompts",
+	"name": "Default color scheme for shell prompts",
 	"colors": {
 		"black": 16,
 		"white": 231,
@@ -10,6 +10,7 @@
 		"brightgreen": 148,
 
 		"darkestcyan": 23,
+		"darkcyan": 74,
 		"mediumcyan": 117,
 		"brightcyan": 159,
 
@@ -55,6 +56,7 @@
 	"groups": {
 		"user": { "fg": "white", "bg": "darkblue", "attr": ["bold"] },
 		"superuser": { "fg": "white", "bg": "brightred", "attr": ["bold"] },
+		"virtualenv": { "fg": "white", "bg": "darkcyan" },
 		"branch": { "fg": "gray9", "bg": "gray2" },
 		"cwd": { "fg": "gray9", "bg": "gray4" },
 		"cwd:current_folder": { "fg": "gray10", "bg": "gray4", "attr": ["bold"] },

powerline/config_files/themes/shell/default.json

@@ -9,6 +9,9 @@
 			{
 				"name": "user"
 			},
+			{
+				"name": "virtualenv"
+			},
 			{
 				"name": "cwd",
 				"args": {

powerline/config_files/themes/shell/default_leftonly.json

@@ -9,6 +9,9 @@
 			{
 				"name": "user"
 			},
+			{
+				"name": "virtualenv"
+			},
 			{
 				"name": "branch",
 				"before": " "

powerline/segments/common.py

@@ -211,3 +211,7 @@ def network_load(interface='eth0', measure_interval=1, suffix='B/s', binary_pref
 		rx_diff=humanize_bytes((b2[0] - b1[0]) / measure_interval, suffix, binary_prefix),
 		tx_diff=humanize_bytes((b2[1] - b1[1]) / measure_interval, suffix, binary_prefix),
 		)
+
+
+def virtualenv():
+	return os.path.basename(os.environ.get('VIRTUAL_ENV', '')) or None