Wrapped the every string literals with _(...) function.
The _() function resides in "app/src/processing/app/I18n.java",
which translates the UI texts using "Resources_XX.properties" file
where XX is the locale code.
I provided the properties file for the ja (Japanese) locale.
I created this file using "xgettext" and "msgcat" commands.
"i18n_update.{py,sh}" files are the tool I used to do that.
Change in "app/build.xml" is to include the properties files
in jar file.
