regressions_SUITE will have code snippets which previously crashed the compiler.

This commits includes a test for Maps crash in beam_bool.

Before beam_split the get_map_elements instruction is still in
blocks and the helper function in beam_jump did not reflect this.

Reported-by: Quviq twitter account

* bjorn/compiler/spurious-warning:
  sys_core_fold: Eliminate warnings for unused terms in effect context
  sys_core_fold: Eliminate warnings for unused terms

* bjorn/compiler/doc:
  Update compiler documentation

(Sneaking in OTP-12769 here which is a release note for syntax_tools.
Sorry about that.)

Language cleaned up by the technical writer tmanevik from
Combitech. Proofreading and corrections by Björn Gustavsson.

* egil/opt-compile-time/OTP-12774:
  stdlib: Relax erl_anno_SUITE:is_anno/1 test
  Update primary bootstrap
  compiler: Use Maps as type information
  compiler: Use Maps instead of dict in beam_jump
  compiler: Use cerl_sets instead of gb_sets in beam_type
  compiler: Use Maps instead of gb_trees in beam_dead
  compiler: Use cerl_sets instead of gb_sets in beam_jump
  compiler: Use cerl_sets instead of sets in v3_kernel
  compiler: Use cerl_sets instead of gb_sets in sys_core_fold
  compiler: Add cerl_sets module
  compiler: Scope uses gb_sets not gb_trees
  beam_dict: Use Maps to map function name indices
  beam_dict: Use Maps to map line indices
  beam_dict: Use Maps to map atom indices
  v3_codegen: Use Maps to map local functions
  v3_life: Refactor variable db
  compiler: Use lc instead of map/1 in v3_codegen
  stdlib: Optimize erl_anno:is_string/1

Conflicts:
	bootstrap/lib/kernel/ebin/inet_dns.beam
	bootstrap/lib/stdlib/ebin/erl_anno.beam
	bootstrap/lib/stdlib/ebin/erl_lint.beam