Use correct field separator in keywords.txt

The Arduino IDE requires the use of a single true tab separator between the keyword name and identifier. When spaces are used rather than a true tab the keyword is not highlighted.

Reference:
https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5:-Library-specification#keywords

Author: per1234

keywords.txt

@@ -10,9 +10,9 @@ PS2KeyRaw	KEYWORD1
 #######################################
 # Methods and Functions (KEYWORD2)
 #######################################
-begin       KEYWORD2
+begin	KEYWORD2
 available	KEYWORD2
-read	    KEYWORD2
+read	KEYWORD2
 
 #######################################
 # Constants (LITERAL1)