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.
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.

To adapt the changed filename, also changed the references in
Makefile.am and table.txt
Added documentation line for the new table.txt field

Added the description for the new "Simplified Chinese equivlant character"
field. Also provided example.
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.
Updated CLI to output the new simpchar field

Updated CLI to output the new simplified variant field. Users may
examine the results with CLI.
Modify unit test for the new API change

Modified the cangjie_char_new() statments to add simpchar.
Also added the assertion of simpchar field.

Should fix the error in Travis CI building process.

Changes from ee038be to to this commit should be sufficient to
resolve #40.