v0.32.0 ALTER DROP, ADD, MODIFY, RENAME, etc statements support

v0.32.0

Improvements

1. Added support for several ALTER statements (ADD, DROP, RENAME, etc) - #215
   In 'alter' output added several keys:
   1. 'dropped_columns' - to store information about columns that was in table, but after dropped by alter
   2. 'renamed_columns' - to store information about columns that was renamed
   3. 'modified_columns' - to track alter column changes for defaults, datetype, etc. Argument stores previous columns states.

Fixes

1. Include source column names in FOREIGN KEY references. Fix for: #196
2. ALTER statement now will be parsed correctly if names & schemas written differently in create table statement and alter.
   For example, if in create table you use quotes like "schema_name"."table_name", but in alter was schema_name.table_name - previously it didn't work, but now parser understand that it is the same table.