Mostly avoids including eval.h, ex_cmds2.h and ex_docmd.h in other
headers.

This avoids including ex_eval.h in any other header, thus preventing
future circular includes.

The "cp" stands for codepoint.

Closes https://github.com/neovim/neovim/issues/7401

fix(lua): don't leak memory on error

Work on https://github.com/neovim/neovim/issues/459

The size of long varies depending on architecture, in contrast to the
MAXLNUM constant which sets the maximum allowable number of lines to
2^32-1. This discrepancy may lead to hard to detect bugs, for example
https://github.com/neovim/neovim/issues/18454. Setting linenr_T to a
fix maximum size of 2^32-1 will prevent this type of errors in the
future.

Also change the variables `amount` and `amount_after` to be linenr_T
since they're referring to "the line number difference" between two
texts.

Work on https://github.com/neovim/neovim/issues/459

Add space around arithmetic operators '+' and '-'.
Remove space between back-to-back parentheses, i.e. ')(' vs. ') ('.
Remove space between '((' or '))' of control statements.
Add space between ')' and '{' of control statements.
Remove space between function name and '(' on function declaration.
Collapse empty blocks between '{' and '}'.
Remove newline at the end of the file.
Remove newline between 'enum' and '{'.
Remove newline between '}' and ')' in a function invocation.
Remove newline between '}' and 'while' of 'do' statement.