support field properties from NULL to NOT NULL
support field properties from NOT NULL to NULL

[summary]
1 add implement in check_if_supported_inplace_alter of tianmu handler;
2 add implement in inplace_alter_table of tianmu handler;
3 add implement in commit_inplace_alter_table of tianmu handler;

fix 1:#818 Master slave synchronization - There will be too many tuples problem

Cause:
Tianmu::dbhandler::TianmuHandler::current_position This variable is not initialized. In some cases,
a large value may cause too many tuples problem.
Solution: Initialize the variable

fix 2:#819 Master slave synchronization - Primary key conflict problem

Solution: Modify the modification logic of master slave synchronization, so that the delete and update operations do not follow the primary key logic

Supplement

sql/sql_insert.cc
Fix the problem that the insert statement will not generate binlog in the delayed insert mode
storage/tianmu/handler/tianmu_handler.cpp
Fix the binlog error of the line format generated by the tianmu engine

[summary]
1 class member variable refactor：exproter directory;
2 class member variable refactor：loader directory;

[summary]

NULL-->nullptr
namespace "DBHandler"-->"handler"
class TianmuHandler-->ha_tianmu
sdb-->tianmu
functions in ha_my_tianmu.cpp all renamed with prefix "ha_my_tianmu_xxx"

- Add Chinese directory configuration
- Remove unnecessary styles
- Update RodaMap

 [summary]
 1.class member variable refactor：common directory;

class member variable refactor：handler directory

[summary]
1 class member variable refactor：compress directory;
2 class member variable refactor：types directory;

update Release Notes and Installation Package

Eplain query Q4 lead to crash,because assert(join == NULL) in SELECT_LEX::optimize() function.
the root cause is that the new join is not released. we can use sl->cleanup(true) to release it

Delete the incorrect configuration and modify the Chinese directory

Cause:
When the date in MySQL is 0, the value is considered to be null. MySQL handles this problem. If you query the statement of isull,
you will convert isnull to=0. This problem is that the value with the date of 0 is inserted into the table.
The query and deletion results of the tianmu engine are not consistent.
The reason for the inconsistency is that the syntax parsing logic of the query and deletion of tianmu is not the same
Solution:
Unified query logic and modification logic for date format processing.
Keep the phenomenon of tianmu consistent with innodb.