Language: Support referring directly to inherited scopes.

find_inherit() now falls back to the most recent scope if
it is not present among the direct scopes. This is useful
when having deeply nested inherits, and allows for eg:

  container::m_obj::base_obj::m_name::create();

to possibly be replaced with just

  m_name::create();
decode_value: id_to_program() now knows about Nettle.
Compiler: Warn about case values that are not enumerable.

Constant objects and the like are not a good idea to have in
case statements, since their ordering will depend on (among
other things) compilation order, which means that they will
currently likely break for dumped programs.
CHANGES: Added some notes about new language features.
Backend: Darwin's poll(2) is based on kqueue(2), so there's no
benefit to supporting poll independently.
Suppress warning from dumpmaster.pike due to non-enumerable case values
Language: Improve backward compat for inherit specifiers.

Inherit specifiers are now only looked up in indirect
inherits when not found as any direct inherit:

  The priority order is as follows:

  1: Direct inherits in the current class.

  2: The name of the current class.

  3: 1 & 2 recursively for surrounding parent classes.

  4: Indirect inherits in the current class.

  5: 4 recursively for surrounding parent classes.

  6: this_program.

Note that a deep inherit in the current class trumphs
a not so deep inherit in a parent class (but not a
direct inherit in a parent class). To select the deep
inherit in the parent class in this case, prefix it
with the name of the parent class.

This should be fully backward compatible except for the case
where there's a deep inherit with the name "this_program".
Compiler: Fixed some parent access issues.

The parent could get lost if the symbol was an inherited local constant.
Compiler: Git rid of some symbol mangling.

Fixes lookup of deep inherits.
Testsuite: Added some inherit lookup tests.
Fixed switch-on-object warning.
Fixed switch-on-object warning.
Fixed last switch-on-non-enumerable that broke the test suite.
Use cond_begin/cond_end instead of cond_resolv, since it breaks with larger input.
Made the packet size configurable. Setting the size to 1400 improves conditions when there are packet loss, as it avoids block-of-line for the integrity check of the TLS record. The tradeoff is more overhead.
block_allocator: do not allocate too large bitvector
Added support for SALSA20. A bit of copy and paste in the cipher implementation, but it felt excessive to add #cmod_define_block/#cmod_end_block or similar meta programming.
Fixed comment.
Nettle.SALSA20: Added some AutoDoc.

Enabled the disabled documentation of Nettle.SALSA20.

Added some documentation of set_iv().

Also made some minor fixes to the key length validator.
Do not fail if the file is already closed from the remote side.