Fix compiler warnings for -Wimplicit-int-conversion part1

[ma8ma]

整数型の変数をサイズが小さい整数型へ暗黙的に変換している箇所は精度が失う可能性があるとclangに指摘されたため明示的にキャストstatic_cast<...>()を使ったり、整数型を変更してコンパイラに意図した変更であると伝えます。

clang 17のレポート (file pathを一部省略)

src/article/drawareabase.cpp:2444:33: warning: implicit conversion loses integer precision: 'const int' to 'char' [-Wimplicit-int-conversion]
src/article/drawareabase.cpp:2451:20: warning: implicit conversion loses integer precision: 'const int' to 'char' [-Wimplicit-int-conversion]
src/article/drawareabase.cpp:2460:20: warning: implicit conversion loses integer precision: 'const int' to 'char' [-Wimplicit-int-conversion]
src/article/drawareabase.cpp:2467:16: warning: implicit conversion loses integer precision: 'const int' to 'char' [-Wimplicit-int-conversion]
src/article/drawareabase.cpp:2471:12: warning: implicit conversion loses integer precision: 'const int' to 'char' [-Wimplicit-int-conversion]
src/article/layouttree.cpp:122:23: warning: implicit conversion loses integer precision: 'const int' to 'unsigned char' [-Wimplicit-int-conversion]
src/control/controlutil.cpp:291:18: warning: implicit conversion loses integer precision: 'const guint' (aka 'const unsigned int') to 'char' [-Wimplicit-int-conversion]
src/dbtree/nodetreebase.cpp:864:25: warning: implicit conversion loses integer precision: 'const int' to 'unsigned char' [-Wimplicit-int-conversion]
src/dbtree/nodetreebase.cpp:866:31: warning: implicit conversion loses integer precision: 'const int' to 'unsigned char' [-Wimplicit-int-conversion]
src/jdlib/misccharcode.cpp:493:22: warning: implicit conversion loses integer precision: 'const char32_t' to 'char' [-Wimplicit-int-conversion]
src/jdlib/misccharcode.cpp:497:31: warning: implicit conversion loses integer precision: 'unsigned int' to 'char' [-Wimplicit-int-conversion]
src/jdlib/misccharcode.cpp:498:31: warning: implicit conversion changes signedness: 'unsigned int' to 'char' [-Wsign-conversion]
src/jdlib/misccharcode.cpp:502:31: warning: implicit conversion loses integer precision: 'unsigned int' to 'char' [-Wimplicit-int-conversion]
src/jdlib/misccharcode.cpp:503:31: warning: implicit conversion changes signedness: 'unsigned int' to 'char' [-Wsign-conversion]
src/jdlib/misccharcode.cpp:504:31: warning: implicit conversion changes signedness: 'unsigned int' to 'char' [-Wsign-conversion]
src/jdlib/misccharcode.cpp:508:31: warning: implicit conversion loses integer precision: 'unsigned int' to 'char' [-Wimplicit-int-conversion]
src/jdlib/miscutil.cpp:1476:39: warning: implicit conversion loses integer precision: 'int' to 'unsigned char' [-Wimplicit-int-conversion]
src/jdlib/miscutil.cpp:1477:43: warning: implicit conversion loses integer precision: 'int' to 'unsigned char' [-Wimplicit-int-conversion]