Bash: New aliases + prevent duplicates in $PATH + some refactoring.

docs/Bash.md

@@ -33,6 +33,10 @@
 
 * *marked* → open -a marked
 
+* *e* → subl
+
+* *+x* → chmod +x
+
 * *md <dir>* → Make directory and `cd` to it.
 
 * *f <what>* → Recursively find file in current directory.
@@ -80,6 +84,10 @@ Get a character’s Unicode code point: `£` → `\x00A3`.
 	
 Make HTTP request using respective method.
 
+### headers <URL>
+
+Print HTTP headers of a given URL.
+
 ### gz <filepath>
 
 Get gzipped file size.