Added "simplified variant" field into table.txt

The current table.txt provides no data for the "type traditional
output simplified" features.

This commit added a new field of "simplified variant" data into
table.txt so db_builder can build data on. Which provides building
block for the "type traditional output simplified" feature.

Please note that this commit will break builds. The following
commit(s) will fix build by adpoting this change into db_builder.
Modify dbbuilder to fit the new table.txt format

Added the simpchar field into database. Updated the dbbuilder so it
will parse and insert the "simplified variant" field data into the
database.

TODO: Change the documentation of README.table.rst
TODO: Actually make use of the data in libcangjie (breaks API)
Remade README.table.rst to README.table.md

All other README and documentations in this project is in markdown
format. It make sense to change this file to markdown too.

Also removed all number words from the file to make it easier to
change..
Added documentation line for the new table.txt field

Added the description for the new "simplified variant" field.
Added simpchar to cangjiechar (API break)

This commit added "simplified variant" field result into a new
struct field simpchar in cangjiechar. SQL queries are updated to
query and pass the data correctly.

TODO: modify the CLI tool to test the query result
Updated CLI to output the new simpchar field

Updated CLI to output the new simplified variant field. Users may
examine the results with CLI.

Until now, the changes should be able to meet #40 (Provide "type
Traditional output Simplified" interface).