ticket:11018: Refactor date format string mapping code (ICU4J)

ticket:11018: Refactor date format string mapping code (ICU4J)

To make this code more maintainable: Make mapping tables zero based, add
a table to tell if a character can be used to define a field in a format
string (instead of now rather long-winded character range expressions)
and make all lookup tables accessed through helper functions.

R=rocketman@google.com

Committed: http://bugs.icu-project.org/trac/changeset/36900

[tkeep, 2014-12-15 20:49:50]

Thanks for all of this work fredrick. Looks good to me.

https://codereview.appspot.com/190960043/diff/1/main/classes/core/src/com/ibm...
File main/classes/core/src/com/ibm/icu/text/SimpleDateFormat.java (right):

https://codereview.appspot.com/190960043/diff/1/main/classes/core/src/com/ibm...
main/classes/core/src/com/ibm/icu/text/SimpleDateFormat.java:1359: -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
Optional: It would be nice if we could somehow have all the static data for each
letter in one place. Maybe an array of struct. But I understand that JAVA isn't
well suited for that since everything except primitive types has to be heap
allocated. While doing an array of structs might be a win for C++, I don't think
it would be worth it for JAVA.

[roubert (google), 2014-12-19 07:28:28]

Committed patchset #1 (id:1) manually as 36900 (presubmit successful).