namespace: restore namespace import support

Commit 8e28d066 "fixed" infinite namespace import
recursion by simply disabling support for import.

This commit restores support by detecting self-import.

Signed-off-by: Steve Bennett <steveb@workware.net.au>
alias: don't rely on internal list never shimmering

It is possible for the alias prefix to shimmer, especially
if the prefix is a list with a single element

Signed-off-by: Steve Bennett <steveb@workware.net.au>
namespace: disallow creation of import loops

Signed-off-by: Steve Bennett <steveb@workware.net.au>
jim.c: string to double conversion error message

Change the error message to match Tcl 8.6

"expected floating-point number" instead of "expected number"

Signed-off-by: Steve Bennett <steveb@workware.net.au>
Install tcltest compatibility package

Allow 3rd party tests to be written and use:

  package require tcltest

Signed-off-by: Steve Bennett <steveb@workware.net.au>
Add more tcl compatiblity

- Add wide() function to [expr] (same as int())
- Small error message changes

Signed-off-by: Steve Bennett <steveb@workware.net.au>
jimsh: change order of default $auto_path

Add directory containing jimsh before JIM_LIBPATH
Helps with running uninstalled jimsh

Signed-off-by: Steve Bennett <steveb@workware.net.au>