Merge pull request #16 from bochecha/master

2 trivial bug fixes
freqdbbuilder: Rename the built executable

This way, it is in the same namespace as all the others
we install.
util: Comment on our utilities

If we ever grow our number of little helper functions, it
might be good idea at some point to start looking into reusing
alternatives from other libraries.

The 2 ones we have currently exist in Boost, so let's keep
track of it, in case we ever decide to switch to it in the
future.
cli: CNY cleanup

This drops all the useless commented code, as well as the unneeded
#include's
dbbuilder: CNY cleanup

This drops some leftover debug code, remove old useless comments, extra
empty lines, etc...
dbbuilder: This is an error

Errors should be written to stderr, not stdout.

This is especially problematic because when running the dbbuilder
at build time, we redirect stdout to /dev/null, and as such would
miss this message.
dbbuilder: Add some comments

The code is about to get slightly more complex, so these
will help.
util: Convert an int to its string representation

This will be useful in a future commit, when refactoring the
frequency management.
dbbuilder: Build the frequency into the main dbs

The goal is to simplify drastically the run-time code, by having all the
information about each character directly into the main cangjie
databases:
  - its code
  - its character
  - its frequency

That means we don't need to install the wordfreq.mb database any more.

Note that this only changes the dbbuilder, it doesn't yet port the main
CangJie class to use the new database format.
dbbuilder: Rename some variables

Hopefully, the new names should be make it clearer that they concern the
result database.
util: Add two new helpers

These will be used in the port of the main library to the
new database format.
cangjie: Port to the new database format

This greatly simplifies the code, now that the frequency is also in the
same database.

Note that all this was done without breaking the external API. :)