This is the staging commit for patch version 1.0.2. #4

This patch update eliminates the warnings by `-Wall` and `-Wextra` on both GCC
11 and Clang 19, fixes an incorrect return value error in `_chkparg()`
effecting every checked subroutine, and improves the safety of some overlooked
signed and unsigned comparisons.
 - Correctly cast `i` to unsigned in `_findnextof()`.
 - Correctly cast `i` to unsigned in `_findnextnotof()`.
 - Added braces to nested `if-while-if` in `_findnextnotof()` to sate GCC.
 - Fixed missing `return` keyword in `_chkparg()` in the case that
 `CREMPTYPATH` should be returned because `path` is `NULL` or `np` is zero.
 - Changed type of `cur` in `_pathnth_i()` to unsigned to fix signed-unsigned
 comparison casting ambiguity.
 - In `crpathisroot()` and `crpathisabs()` now explicitly testing that `i` is
 non-negative and then correctly casting to unsigned for comparison with the
 result of `strnlen()`.
 - Changed type of `j` in `crpathtrivial()` to unsigned to fix signed-unsigned
 comparison casting ambiguity.
 - Correctly cast `i` to unsigned in `crpathtrivial()`.
 - Removed unused variable `j` from `crpathcount()`.
 - Correctly cast `i` to unsigned in `crpathcount()`.
 - Added extra parentheses to assignment in `if` to sate GCC in `crpathlast()`.
 - Added extra parentheses to assignment in `if` to sate GCC in `crpathbase()`.
 - Correctly cast `np` to signed in `crpathbase()`.
 - Removed unused variable `r` in `crpathext()`.
 - Added extra parentheses to assignment in `if` to sate GCC in `crpathhead()`.
 - Added extra parentheses to assignment in `if` to sate GCC in `crpathtail()`.
 - Added extra parentheses to assignment in `if` to sate GCC in `crpathnth()`.
 - Removed unused subroutine `_isach()`.
 - Correctly cast `np` to signed in `_getpathsz()`.
 - Changed type of `k` in `_scanpaths()` to unsigned to fix signed-unsigned
 comparison casting ambiguity.
 - Added extra parentheses to assignment in `if` to sate GCC in `_scanpaths()`.
 - Casting `np` to `void` in `_accumpart()` to portably mark it as unused.
 - Casting `npaths` to `void` in `_accumpath()` to portably mark it as unused.
 - Changed type of `k` in `_catpaths()` to unsigned to fix signed-unsigned
 comparison casting ambiguity.
 - Changed type of `k` in `crvpathcat()` to unsigned to fix signed-unsigned
 comparison casting ambiguity.
 - Rolled version to 1.0.2.
 - No longer using `stderr` in example program in the `crpathnth()` test.