Fixed issues with taxonomy translation, reimplementing with object translation and advanced caching.

Fixed issues with setting string value and language code not passed around. Added per-textgroup hidden debugging option

Improved field translations and string handling. String objects are passed around instead of complex data arrays.

Issue #1185644: API improvements. Added i18n_string_object() to handle strings. Adding better caching for strings.

Issue #1185644: API improvements. Reordered functions. Improved object translation with some static caching. Using object translation for i18n_contact.

Issue #1169120: Changed Delete strings from textgroup when uninstalling module. Error after uninstalling the module.

Issue #1186996: Fixed Fatal error: Call to undefined function get_strings() in i18n_string()/i18n_string().module on line 744.

Issue #1185644: API improvements. Added hook_i18n_string_objects() for a module to return translatable objects, replacing string_list(). Added 'list callback' for i18n object metadata.

Issue #1185644: API improvements. Improved format access checking. Renamed i18n_string_object to i18n_string_object_wrapper

Issue #1067618: Updating to work with l10n_client. Added some API functions to enforce permissions and formats.

Issue #1067618: Updating to work with l10n_client + string context support. Fixed issue with filter permission checking.

Issue #1157826 by dereine: Create a way to write a translation/localization string into the database

Issue #1114602 by Gábor Hojtsy, yoroy: improve usability of i18n_string based modules dramatically by providing an API to expose a translation tab on objects
Reference implementation of that on blocks.