* Avoids boot time mutation of REGISTER constant
* Allows to define project specific expression parsing
* Avoids custom (slow) serialization of Expression objects speeding up
reporter / killer IPC
* Improve specification
* Improve integration API as it now finally references an object the config
* Allow reproduction of syntax from Expression#syntax
* Allow instantiation of Expresssion objects without generating the
syntax, much nicer for most specs & internal code, avoids generating
a string to parse it into an expression
* Fix LSP violation in Mutant::Matcher namespace
* I do not use 1.9.3
* Also keeping them in each file increases mental overhead (true it *can* be autoamted)
* None of the files encodes NON ASCII chars.
* I do not expect it makes any difference, since nobody programmatically
will consume strings generated by mutant under the assumption they are UTF-8 encoded.
* 1.9.3 Users have to deal with the encoding fuckup under ruby anyways.
