Major rewrite. Sections Tags, Emerge, Change Log and Authors

Major rewrite.  Sections Tags, Emerge, Change Log and Authors
moved to maintaining.texi.  Some sections reordered.

Node Misc for Programs moved to just before the language-specific sections.

New node Defuns contains an intro plus the old
Defuns node (now renamed Moving by Defuns)
as well as Imenu, Which Function, and a node
Left Margin Paren to explain the convention about this.

New node Parentheses now documents M-x check-parens.
It contains subnodes Expressions, Moving by Parens, and Matching.
Expressions and Moving by Parens contain the material
formerly in Lists and List Commands, but divided up differently.
The section Balanced Editing has been deleted.

Most of the C indentation customization (all except c-set-style),
has been replaced with a reference to the C Modes manual.

Documentation now is divided into three subsections.

Some rewrites in the Program Indent section about
C-u TAB and C-M-q.