Optimize the parameters for the typing algorithm

The new set of parameters are optimized for both
keystroke savings and regression test scores.

This change is corresponding to the patch 6 of
Change-Id: Ib8439a85de26cbbba58837344717f0acbfcf0ab0
in the regression test repository.

Here is the link to the doc analyzing the
“nnow → know” case:
https://docs.google.com/a/google.com/document/d/1XIHfAHLlP1f3F8R-u7yxPGWcP58tokygzN_lQKXFFgM/edit

Here is the link to the spreadsheet showing
the diff of the words with frequencies >= 10
in en_user_log_phones_2011_08.csv.
https://docs.google.com/a/google.com/spreadsheet/ccc?key=0Am_RQlV4zC6SdFFVTlhJT0RLUENCWWZOZ3JQTUpMQ2c&usp=drive_web#gid=0

Updated TRT Results for this change:
[Category diff]
+1     783
-1     717
+2      20
-2      34
+3      34
-3      20
+4     575
-4     777
+5     765
-5     755
+6     785
-6     666
+7     479
-7     472

[Weighted category diff]
+1     999
-1     965
+2      21
-2      35
+3      35
-3      21
+4     804
-4     980
+5     970
-5     971
+6     954
-6     831
+7     645
-7     625

Bug: 10613502

Change-Id: I5cd447673a196ad5af641a2118602bec879bdefb