Added namespace feature.  Symbols are not namespaced yet.

(ns <namespace>) will set the current namespace and (ns) will return it to global namespace.  Namespaced symbols is not done yet.
Merge branch 'development' into namespaces

Conflicts:
	Nerd/src/Shell/Shell.c
Lexical analyser understands namespaces.
Fish prompt added.
Fixed Krull.n.
Merge branch 'development' into namespaces
Use '.' for namespaces now - not '/'.
Added tables.
Added set! functionality.

Also fixed a lot of garbage collection/marking bugs.
Fixed a bug and added check in atom->string code.
Added table look up.
Added has-key? built-in and implemented NeTableHasKey().
Merge branch 'refs/heads/namespaces' into hash-tables.

Conflicts:
	Nerd/src/Core/NeLibCore.c
	Nerd/src/Core/Nerd.c
	Nerd/src/Shell/Shell.c
Merge branch 'development' into namespaces

Conflicts:
	Nerd/src/Shell/Shell.c
Merge branch 'refs/heads/namespaces' into hash-tables

Conflicts:
	Nerd/src/Shell/Shell.c
Added pool system.

Refactored cell heap management to use the new pool system.
Fixed reporting of numbers when NE_DEBUG_DESTROY is set.
Environments now use tables.

Simplified table API (combined get value with has key).
Removed array API - tables will be arrays as well.
Changed namespace divider to '/' so we can use '.' just for tables.
Improved some comments.
Altered symbol API to store symbols and values in tables.
Tables use dot notation for field lookup.

Changed prompt - got rid of the ascii fish.
Namespace and tables use '.' for a divider.
Display of (quote value) is now 'value.
Tables use [] brackets.
Fixed bug in NeSet.
Updated todo list.