In order to guarantee that Hammer can build on Windows, an appveyor.yml
and associated build scripts will build hammer and its examples. The idea
is that as soon as the appveyor.yml exists in the repository, pull
requests that would impede Windows portability would be immediately
detected.

The scripts expect CL.EXE to be in the path, and will produce their
results in build/

The highest level of warning is enabled on CL.EXE, minus warnings that
bring CL.EXE to a level that ressembles C99. The only notable warning
that was disabled is the one that tells you about implicit truncating
conversions.

Hammer's source code has quite a few implicit conversions say from a 64bit
unsigned integer to a integer of a lesser size (signed or otherwise)

Fix #133

Print user defined token type while pretty printing

The pretty printing format chosen is USER:<token name>

We use the registry function `h_get_token_type_name` which returns 0
when no name has been defined. This will print (null) as a token name.

Usability improvements from the tutorial

Algebraic Generating Functions from parser

Now we can do things like:

# copy-paste from output
ring.<t,L,tie,Cn,M,Ln,I,D,J,Rn,A,K,F,G> = QQ[]
ID = ring.ideal(L - (1*Cn*t),tie - (1*Ln*t),Cn - (1*I + 1*J),M - (1*t^2),Ln - (1*D + 1*L + 1*M),I - (1*Rn*t),D - (1*Rn*t),J - (1*Ln*t),Rn - (1*F + 1*G + 1*K),A - (1*tie),K - (1*t^2),F - (1*Ln*t),G - (1*Cn*t))

# we are interested in tie in terms of t; so we want to remove anything not these two:
ID.elimination_ideal([L,Cn,M,Ln,I,D,J,Rn,A,K,F,G])

# output from this SageMath command is
# Ideal (t^3 + 2*t^2*tie + t*tie - tie) of Multivariate Polynomial Ring in t, L, tie, Cn, M, Ln, I, D, J, Rn, A, K, F, G over Rational Field
# which we can solve for tie to get tie = t^3/(1-t-2*t^2) just as expected

Update from trunk

Add monadic bind combinator h_bind

Free res_unamb

Add some missing type conversions to make h_read_bits work with count>32

Descend properly in h_seq_index_path