Exponential 4 database charset conversion

Exponential 4 database charset conversion
========================================
Converts db's charset from arbitrary encoding to utf8.
Supports mysql and postgresql.

Usage:
$ ./bin/php/ezconvertdbcharset.php -s <your_siteaccess>

Params:
$ ./bin/php/ezconvertdbcharset.php --help


Troubleshooteing
----------------
* Problem with collation

  Symptom:
  the script can fail on MySQL with message like:
  "Query error: Duplicate entry 'bjön' for key 2. 
   Query: ALTER TABLE ezsearch_search_phrase CONVERT TO CHARACTER SET utf8"
  
  Description:
  - the original collation is 'latin1_swedish_ci';
  - column 'phrase' of the 'ezsearch_search_phrase' is defined as unique key,
    thus MySQL creates index for this column during conversion;
  - the 'latin1_swedish_ci' distinguishes characters 'o', 'ö'('o' with umlaut)
    and 'ø'('o' with slash). Thus the original 'phrase' column can have values
    with all 3 characters, like:
    +-----------+
    | phrase    |
    +-----------+
    | abco      |
    | abcö      |
    | abcø      |
    +-----------+
  - there is no approprite 'utf8_...' collation which can distinguish those
    chars. 

  Solution:
  - use 'GROUP BY' and some collation other then original to remove problem
    rows. The new collation should behave as wanted "utf8_..." collation.
    f.ex. 'utf8_general_ci' doesn't distinguish 'ö' and 'ø', the 
    'latin1_danish_ci' as well. Thus need to do:
    (1) mysql> create table ezsearch_search_phrase_1 as select min(id) as id,
                  phrase,
                  sum(phrase_count) as phrase_count,
                  sum(result_count) as result_count 
                from ezsearch_search_phrase
                group by phrase
                collate latin1_danish_ci;

    (2) mysql> truncate ezsearch_search_phrase;
    (3) mysql> insert into ezsearch_search_phrase select * 
                from ezsearch_search_phrase_1;
    (4) mysql> drop table ezsearch_search_phrase_1;

  - while playing with grouping and collations it can be useful to check that
    problem gone without running the script. f.ex. if desired  collation is
    'utf8_general_ci' and to check whether it's enough to do grouping using 
    'latin1_danish_ci':
        mysql> create unique index ezsearch_search_phrase_phrase 
                on ezsearch_search_phrase_1(phrase);
    (5) mysql> alter table ezsearch_search_phrase_1
                convert to character set 'utf8'
                collate 'utf8_general_ci';

  - if (5) failes the step (1) should be repeated with another collation
    (latin1_german1_ci, latin1_german2_ci) like:
        mysql> create table ezsearch_search_phrase_2 as select min(id) as id,
                    phrase,
                    sum(phrase_count) as phrase_count,
                    sum(result_count) as result_count
                from ezsearch_search_phrase_1
                group by phrase
                collate latin1_german1_ci;