REDUCE Code

tidy up the code to reduce some duplication and fix the odd typo;

add code to numerically evaluate the Weierstrassian functions when they
degenerate to elementary functions, i.e. when the discriminant is zero;

add new operators to calculate the lattice roots and lattice generators
as functions of the invariants;

add an operator to return a canonical basis for a rectangular or rhombic
lattice given two half-periods w1 & w3 or return NIL if w1 and w3 do not
generate a rectangular or rhombic lattice;

generalise somewhat the code to numerically evaluate epsilon_w and
epsilon_w1 for rhombic and rectangular lattices. These routines are
still somewhat restricted and work is in progress to generalise these;

add several rules primarily to support power series expansion of the
Weierstrass and Weierstrass Zeta functions. Expansion of the Weierstrass
sigma function remains a problem.

ellipfn.tex: Changes to the manual pages to document the new features
provided by efweier.red.

ellipfn.rlg: Necessary update log file due to an previous error in the
differentiation rule for Weierstrass1.