Forthish is a very small runtime compiler that displays source by
decompiling object code.  Forthish does not pretend to be a full Forth; it's
more an exercise in minimalism and an experiment in runtime generation and
decompilation.

To run example:
	make && echo ok && ./forthish data/include.f data/factorial.f
	12 loop i 1 + . 9 emit i 1 + factorial . cr ;
View the words available:
	words ;
To quit: CTRL-D

Forthish scans a word and executes it.  It does not have an 'interpret'
mode.  The function of most words is to place code to call the function's
code into the stage buffer.  Executing a semicolon runs the code in the
stage.  The colon word will place code to create a definition in the stage.

Forthish does not recognize integers natively.  Instead, the commonly used
integers are named in an enumeration in data/include.f.  This simplifies the
kernel and inner loop.

Extensions include:
	* 'variable name initialization ;'
	  declare a variable and the code to initialize it
	* 'constant name initialization ;'
	  declare a constant and the code to initialize it
	* 'enum value name1 name2 name3 ;'
	  declare an enumeration of sequential named constants
	  name1 == value, name2 == name1+1, name3 == name2+1
	* 'vector name word1 word2 word2 ;'
	  declare a table of function pointers
	* 'value table switch'
	  add the value to the vector table and branch to that location
	* 'value loop definition-tail ;'
	  execution the definition-tail for i in value..0
	* 'value if definition-tail ;'
	  if value is true the execute definition-tail else return
	* 'value while definition-tail ;'
	  while top of stack is true do execute definition-tail