check_config: assert INI datatypes before comparing limits

[tzuohann]

Problem

A user who puts an inline comment on a limit line — e.g. MAX_LIMIT = 100 # travel, easy to do without carefully reading the manual — is currently served a very confusing error from the pre-run config check:

[JOINT_0]MAX_LIMIT < [AXIS_X]MAX_LIMIT (100 < {100   # travel})

It appears to claim 100 < 100 and points at the wrong problem entirely (a phantom joint/axis limit violation), when the real issue is the stray inline comment.

Cause: the [JOINT_n]/[AXIS_L] limit check in check_config.tcl compares values with Tcl > / <, which silently falls back to string comparison when a value isn't a valid number. The comment text makes the value a string, so the outcome depends on trailing whitespace rather than the numbers. A duplicated key behaves the same way (the multi-valued list is compared as a string).

This affects all of 2.9 — the inline-comment-stripping parser rewrite only exists in master/2.10.

Reproduce

Minimal trivkins config (bad.ini):

[KINS]
JOINTS = 1
KINEMATICS = trivkins coordinates=X
[AXIS_X]
MAX_LIMIT = 100   # travel
[JOINT_0]
MAX_LIMIT = 100

Run the checker against it:

$ tclsh lib/hallib/check_config.tcl bad.ini

Before this patch it reports the phantom [JOINT_0]MAX_LIMIT < [AXIS_X]MAX_LIMIT (100 < {100 # travel}).

Fix

Add assert_ini_datatypes(), run once right after parse_ini, before any comparison. For each [JOINT_n]/[AXIS_L] item it validates the value LinuxCNC actually uses — the first occurrence (IniFile::Find defaults to num=1; the manual, The INI File → Comments, likewise states the first value is used):

• numeric items (limits, vels, accels, scales, PID terms, home vels, …) must pass string is double;
• enum items must match a fixed set, case-insensitively, mirroring LinuxCNC's own caseless parsers (TYPE → LINEAR/ANGULAR; bool set for HOME_*, VOLATILE_HOME, LOCKING_INDEXER).

A non-numeric value containing # or ; additionally reports that inline comments are not allowed and cites the manual section, so the user is pointed at the real mistake:

[AXIS_X]MAX_LIMIT must be numeric, got: <100   # travel>
    Inline comments are not allowed: '#' and ';' start a comment
    only at the start of a line, not after a value. Move the comment
    to its own line. See the LinuxCNC manual, "The INI File" ->
    "Comments": https://linuxcnc.org/docs/stable/html/config/ini-config.html#_comments

Duplicate (multi-valued) keys are not fatal — LinuxCNC uses the first occurrence — so they emit a warning and the array is collapsed to that first value (so the downstream limit comparison uses the same value LinuxCNC would). This subsumes the warn-only warn_for_multiple_ini_values, which is removed.

Testing

Verified with minimal trivkins configs:

Case	Result
inline comment on a limit	error + manual citation (exit 1)
duplicate key, first value valid	warning only, passes (exit 0)
duplicate key, first value has a comment	warning + error on first (exit 1)
clean config	passes (exit 0)