Beginning of a reimplementation in Go.

For now this is just an early proof of concept using my DAWGo library.
Implement loadCEDICT similarly to what we had in Python.
Use log.Fatal instead of panic.
Remove simple segmentation test from main.
Remove path to CEDICT from source code.

Use instead a command-line argument or enviroment variable to point to the file.
Fix wrong help message.
Remove explicit call to Error().

Behind the scenes log.Fatal calls log.Print which works like fmt.Print. That means that the error interface is automatically used to print the error message.
Segment text from stdin/file and write to stdout/file.
Close files after program execution.
Update segmenter to use the new interface of dawg.Prefixes.
Open files in UTF-8 mode.
Write word by word instead of joining all words before writing.
Do not write CR in output.

This makes the output of Python and Go versions equivalent.
The Go version runs way faster. (53s x 3s on msr_test data)
Add benchmark test.
Cut loadCEDICT execution time by about half.
Leave only the fastest implementation of loadCEDICT.
Add benchmark for segment.
Store maximum dictionary key entry.

This information can be useful for reading from a file in a limited buffer of the size of the longest possible word.
Refactor: extract function fSegment.
Refactor: extract longestPrefixWord function.