Add show method for CharTable

[fingolfin]

Right now:

julia> g=genchartab("GL2")
GenericCharacterTables.CharTable{Nemo.QQPolyRingElem}(q^4 - q^3 - q^2 + q, GenericCharacterTables.Cyclotomic{Nemo.QQPolyRingElem}[(1) * exp(2π𝑖(2//(q - 1)*i*k)) (1) * exp(2π𝑖(2//(q - 1)*i*k)) (1) * exp(2π𝑖(1//(q - 1)*i*k + 1//(q - 1)*j*k)) (1) * exp(2π𝑖(1//(q - 1)*i*k)); (q) * exp(2π𝑖(2//(q - 1)*i*k)) 0 (1) * exp(2π𝑖(1//(q - 1)*i*k + 1//(q - 1)*j*k)) (-1) * exp(2π𝑖(1//(q - 1)*i*k)); (q + 1) * exp(2π𝑖(1//(q - 1)*i*l + 1//(q - 1)*i*k)) (1) * exp(2π𝑖(1//(q - 1)*i*l + 1//(q - 1)*i*k)) (1) * exp(2π𝑖(1//(q - 1)*i*k + 1//(q - 1)*j*l)) + (1) * exp(2π𝑖(1//(q - 1)*i*l + 1//(q - 1)*j*k)) 0; (q - 1) * exp(2π𝑖(1//(q - 1)*i*k)) (-1) * exp(2π𝑖(1//(q - 1)*i*k)) 0 (-1) * exp(2π𝑖(q//(q^2 - 1)*i*k)) + (-1) * exp(2π𝑖(1//(q^2 - 1)*i*k))], Vector{Any}[["", [1, 0], Any["A_1", [1, 1]]], ["", [1, 1], Any["A_1", [2]]], ["", [2, 0], Any["A_0", [1]]], ["", [3, 0], Any["A_0", [1]]]], Nemo.QQPolyRingElem[1, q^2 - 1, q^2 + q, q^2 - q], Vector{Any}[["", [1, 0], Any["A_1", [2]]], ["", [1, 1], Any["A_1", [1, 1]]], ["", [2, 0], Any["A_0", [1]]], ["", [3, 0], Any["A_0", [1]]]], Nemo.QQPolyRingElem[1, q, q + 1, q - 1], Function[GenericCharacterTables.var"##CHAR_TABLE#227".var"#1#5"(), GenericCharacterTables.var"##CHAR_TABLE#227".var"#2#6"(), GenericCharacterTables.var"##CHAR_TABLE#227".var"#3#7"(), GenericCharacterTables.var"##CHAR_TABLE#227".var"#4#8"()], Function[GenericCharacterTables.var"##CHAR_TABLE#227".var"#9#13"(), GenericCharacterTables.var"##CHAR_TABLE#227".var"#10#14"(), GenericCharacterTables.var"##CHAR_TABLE#227".var"#11#15"(), GenericCharacterTables.var"##CHAR_TABLE#227".var"#12#16"()], [1, 2], [3, 4], GenericCharacterTables.Parameters{Nemo.QQPolyRingElem}[i ∈ {1,…, q - 1}, i ∈ {1,…, q - 1}, i ∈ {1,…, q - 1}, j ∈ {1,…, q - 1} except 1//(q - 1)*i - 1//(q - 1)*j ∈ ℤ, i ∈ {1,…, q^2 - 1} except 1//(q + 1)*i ∈ ℤ], GenericCharacterTables.Parameters{Nemo.QQPolyRingElem}[k ∈ {1,…, q - 1}, k ∈ {1,…, q - 1}, k ∈ {1,…, q - 1}, l ∈ {1,…, q - 1} except 1//(q - 1)*l - 1//(q - 1)*k ∈ ℤ, k ∈ {1,…, q^2 - 1} except 1//(q + 1)*k ∈ ℤ], nothing, Univariate polynomial ring in q over QQ, Universal Polynomial Ring over Fraction field of univariate polynomial ring, "- Information about the generic character table of \$GL_2(q)\$.\n\n- CHEVIE-name of the table: ``GL2``\n\n- The table was first computed in:\n  {\\sc H.~Jordan}, Group-characters of various types of linear groups,\n  {\\em Amer.\\ J.~Math.} {\\bf 29} (1907), 387--405.\n\n  {\\sc
 I.~Schur}, Untersuchungen über die Darstellung der\n  endlichen Gruppen durch gebrochene lineare Substitutionen,\n  {\\em J.~reine angew.\\ Math.} {\\bf 132} (1907), 85--137.\n\n- See also:\n  {\\sc R.~Steinberg}, The representations of \$GL(3,q)\$, \$GL(4,q)\$, \$PGL(3,q)\$\n  and \$PGL(4,q)\$, {\\em Can.\\ J.~Math.} {\\bf 3} (1951), 225--235.\n ")

This can certainly be improved. At the very least, print the table name, its parameters (including information if anything was specialized via speccharparam or specclassparam), how many characters and classes there are in it...

[fingolfin]

A variant that actually prints the content of the table would also be nice.

And then a variant of that which generates LaTeX, similar to what we have for classical character tables in OSCAR.

[SoongNoonien]

At the very least, print the table name, its parameters (including information if anything was specialized via speccharparam or specclassparam), how many characters and classes there are in it...

A variant that actually prints the content of the table would also be nice.

In the Show.jl file there are some printing functions for generic character tables which cover some of this.

And then a variant of that which generates LaTeX, similar to what we have for classical character tables in OSCAR.

In the PrintToTex directory there some initial implementations to print some of our data types in LaTeX format. But these are very rough and not well documented.

[fingolfin]

We now have some basic show methods thanks to PR #337 and and PR #70.

We could also provide different printing modes following the OSCAR / AbstractAlgebra model as described here:

https://docs.oscar-system.org/dev/DeveloperDocumentation/printing_details/