Add newly added methods and constants to keywords.txt for syntax highlighting.

Author: aentinger

libraries/Arduino_CAN/keywords.txt

@@ -26,6 +26,10 @@ available	KEYWORD2
 read	KEYWORD2
 isError	KEYWORD2
 clearError	KEYWORD2
+setFilterMask_Standard
+setFilterMask_Extended
+setFilterId_Standard
+setFilterId_Extended
 
 getStandardId	KEYWORD2
 getExtendedId	KEYWORD2
@@ -41,3 +45,5 @@ BR_125k	LITERAL1
 BR_250k	LITERAL1
 BR_500k	LITERAL1
 BR_1000k	LITERAL1
+CAN_MAX_NO_STANDARD_MAILBOXES	LITERAL1
+CAN_MAX_NO_EXTENDED_MAILBOXES	LITERAL1