Remove unnecessary call to `getOrigSymbIdForAuxVar` in `computePacModelConsistentExpectationSubstitutionWithComponents` and unnecessary change in `getOrigSymbIdForAuxVar`

Handle PAC models with MCE and a composite target (pac_target_info block)

See merge request Dynare/preprocessor!101

The symbol can be either input:
– as ⟂ in UTF-8 (codepoint U+27C2)
– or as _|_ in ASCII

The old syntax using the “mcp” tag is now obsolete, but kept for backward
compatibility.

Closes: #127

By the way, also improve the terminology used in variable and method names: a
“constraint” is something like “ZLB” or “INEG”, a regime is a state in which
constraints are either binding or relaxed.

Really closes: #103

Ref. dynare#1918

In particular, emit more explicit error messages in the presence of
inconsistencies.

Closes: #103

Closes: #124

Remove globals from extended path

See merge request Dynare/preprocessor!99

Add steady_state_model_present field to modfile.json

See merge request Dynare/preprocessor!100

The old name is still accepted, but will trigger a deprecation warning.

Ref. !96

Ref. !97

Ref. !98

dr_block has been removed