Updated description of GAP 4.8 for the 2nd beta

[olexandr-konovalov]

This is GAPDoc'ified overview of most important changes. It's now in sync with https://github.com/gap-system/gap/wiki/Changes-between-GAP-4.7-and-GAP-4.8

[olexandr-konovalov]

P.S. If you have any suggestions, you may also edit the Wiki at https://github.com/gap-system/gap/wiki/Changes-between-GAP-4.7-and-GAP-4.8 yourself and let me know that I should find changes there, if this will work better for you.

[fingolfin]

Quick remark: the entry on multi index could be highly confusing to outsiders: Because all we did was add the ability to install methods for multi-index access to matrices. However, AFAIK we do not currently install any such methods. In particular, the "example expressions" given on the Wiki page will not work.

[olexandr-konovalov]

@fingolfin I suggest then to formulate it like here:

• [#192] Added ability to install (in the library or packages) methods for accessing lists using multiple indices and indexing into lists using indices other than positive small integers. Such methods could allow, for example, to support expressions like

m[1,2];
m[1,2,3] := x;
IsBound(m["a","b",Z(7)]);
Unbind(m[1][2,3])