Merge pull request #1 from zhuowei/master

Added Automake-based build system
Fixed crash when calling functions with wrong number of arguments.
Fixed incorrect error messages on bad input
Forgot to finish error messages part of the README
Fixed crash when multiplying a variable with something else using parentheses instead of *
Fixed issue with fractions, improved float display, and added log2 and logbase
Fixed plurality in error message
Fixed plurality in README after fix
Special handling of ‘ans’, crash fixes, improved parsing, and lots of refactoring
Added introspection of variables
Allow assigning variables with function values
Better debug info for crashes, and fixed a crash
Fixed two memory leaks
Fixed a couple SEGFAULTs
Fixed some SEGFAULTs
Print prompt to stdout instead of stderr
Fixed crash triggered by f(a,b,c)=1
“Safer” reallocs
Separated variable contexts into locals and globals, documented argument consumption, allowed passing of functions as arguments, and added interpreter reset
Fixed scope bug, improved variable assignment, and fixed parsing of functions with no arguments