Change column definition format (README.table.rst)

Changed column definition format of README.table.rst.

1. Use definition list instead of unordered list.

2. Also, the number word (first, second) at the beginning of lines
   are removed.
3. Fullstops are removed to fit this new format (point form).

4. Also, a column type definition word (string, boolean, integer)
   at the beginning of each lines to improve readabliliy.

The former definition format would be troublesome for those who
want to add or delete column(s). It is also hard to compare the
changes between versions.

The new format would be easier to read and change. And the change
would be easier to read by diff.
Added a simplified char column in table.txt

Added a new column in table.txt to store the simplified variant of
the character(s). This will be used by input-trad-output-simp
feature in the coming commits.

Some note to the new column:

1. The new column content are generated from Unihan database 6.3
   (latest version at 2013-11-02).

2. If a character has a kSimplifiedVariant, it will be filled to
   the new column.

3. If a character has no kSimplifiedVariant, and if it has a
   kZVariant, the kSimplifiedVariant of that kZVariant will be
   filled to the new column.

4. If the character didn't match the cases above, the character
   itself will be filled to the new column.

TODO: dbbuilder would have to change to read this new format.
Update dbbuilder to adapt new table.txt

Changed dbbuilder to read and import the new table.txt format.
Added added a conversion flag to public interface

1. Added a new CangjieConversion enum to the header file
   with the below values:
   - CANGJIE_CONVERSION_OFF           = 0
   - CANGJIE_CONVERSION_TO_SIMPLIFIED = 1

2. Added a new parameter conv (CangjieConversion) to
   cangjie_get_characters()
   (interface only, feature not yet implemented)

3. Changed the benchmark and cli code to adapt the new parameter.
   Both use CANGJIE_CONVERSION_OFF only

4. Added a constant SIMP_QUERY to store a modified version of
   BASE_QUERY to query the chchar_simplified instead of chchar

5. Added a cj_simp_query to type Cangjie for the new query.

6. Added code in cangjie_new to generate this new query along.

TODO: Modify cangjie_get_characters to implement the new interface.
TODO: Modify cli to add the new interface option.
TODO: Modify benchmark code to add benchmark of the new interface.
Implemented conversion in cangjie_get_characters()

Implemented underlying mechanism for the flag conv to work.

Now returns only the simplified variant of the characters.
Fix memory leak bug in cangjie.c

Fixed a memory leak bug created in 06a1acc.
Added CLI option to use simplified variant option

Added a -s / --simplified-variant to use the conv parameter
in cangjie_get_characters().