Refactored g-code parser. Saved 60bytes flash and some ram. Edited Readme.

- Freed up another 60 bytes of flash and 12-24 bytes of stack RAM by
using the pre-allocated IJK arc offset vector that is guaranteed to be
not in use. Only G10 and G28/30 require fetching from EEPROM and
retaining extra data. Both commands use axis words, which rules out
G2/3 arcs using IJK offsets existing in same block. Not ideal, but
every byte helps.

- Edited README.

doc/log/commit_log_v1.1.txt

@@ -1,3 +1,9 @@
+----------------
+Date: 2016-09-27
+Author: Sonny Jeon
+Subject: Update README and clarifications in jogging document.
+
+
 ----------------
 Date: 2016-09-26
 Author: Sonny Jeon