3.0: Rethink prefixes

[iccir]

The compiler currently uses $oj_c_… for classes, $oj_p_… for protocols, $oj_f_… for functions, and $oj_i_… for ivars.

This makes debugging complex, especially for ivars.

If we assume that release builds are always going to be squeezed, could we shorten/simplify the prefixes and renaming of functions for debug builds?

In any case, $oj_ should be some variant of $ns_

[iccir]

Here's a table showing the changes to prefixes and special variables. For most of these, $oj_ was changed to N$_.

oj	NilScript	Description
$oj_oj	N$$_	nilscript root variable used by compiler
$oj_id	N$_id	Runtime global object counter
$oj_super	N$_super	Runtime function to obtain superclass
$oj_unused	N$_unused	Type checker: placeholder
$oj_$AtEachGetMember	N$_atEachGetMember	Codegen: @each
$oj_$AtEachTest	N$_atEachTest	Codegen: @each
$oj_rest	N$_rest	Codegen: rest parameter for TypeScript
$OJAnonymousEnum…	N$_anonymousEnum…	Prefix for anonymous @enum names
$oj_C_…	N$_C_…	Static class prefix (Typechecker only)
$oj_c_…	N$_c_…	Class prefix
$oj_e_…	N$_e_…	Enum prefix (Typechecker only)
$oj_f_…	N$_f_…	Method prefix
$oj_i_…	N$_i_…	Ivar prefix
$oj_m	N$_m	Instance method object passed into makeClass callback
$oj_P_…	N$_P_…	Static protocol prefix (Typechecker only)
$oj_p_…	N$_p_…	Protocol prefix
$oj_s	N$_s	Class method object passed into makeClass callback
$oj_t_…	N$_t_…	Prefix used for temporary variables
$oj_$Base	N$_Base	Typechecker
$oj_$Combined	N$_Combined	Typechecker
$oj_$Globals	N$_Globals	Typechecker
$oj_$id_intersection	N$_IdIntersection	Typechecker
$oj_$id_union	N$_IdUnion	Typechecker
$oj_$Runtime	N$_Runtime	Typechecker
$oj_$StaticBase	N$_StaticBase	Typechecker
$oj_$StaticCombined	N$_StaticCombined	Typechecker
$oj_SEL	N$_Selector	Typechecker

Squeezer prefixes will be defined as N$ followed by a non-_ and non-$ character. Hence, squeezer prefixes match the regexp N\$[A-Za-z0-9]+

The prefix N$$ is reserved for future use.

Regarding ivars: per #153, generated identifiers for ivars will no longer have the class name in them. This should help with debugging. We're going to add a new --simple-ivars option to further ease debugging (this will be in #153).

[iccir]

This is now in the 3.0 branch.