[rtext] Fix TextToPascal()/TextToCamel() truncating text after a separator

[MaxFreedomPollard]

TextToPascal() and TextToCamel() drop everything after an underscore unless the character right after it is one they explicitly handle. TextToPascal() (src/rtext.c:2186) handles a-z and 0-9, TextToCamel() (src/rtext.c:2270) handles only a-z. For anything else neither branch runs, buffer[i] keeps the zero from the memset() at the top of the function, and the returned string ends right there.

So TextToPascal("text_UTF8_load") returns "Text", and TextToCamel("sound_3d_mix") returns "sound". An upper case letter after the separator truncates both, a digit after the separator truncates TextToCamel(), and two underscores in a row truncate both.

The same code also reads one byte past the string. When _ is the last character, j++ lands on the \0, neither branch matches, and then the loop increment moves j one further before the condition reads text[j].

This skips the whole run of separators, stops when that reaches the end of the text, and copies a character that has no upper case form as it is. That last else also covers digits, so it replaces the 0-9 branch TextToPascal() had.

Verified at a2cc9b1 on macOS arm64 with Apple clang 17, CMake configured with -DBUILD_EXAMPLES=ON. The program below links against the built libraylib.a and opens no window. Before the change:

input            TextToPascal   expected            TextToCamel    expected       
-------------------------------------------------------------------------------------
hello_world      HelloWorld     HelloWorld     ok   helloWorld     helloWorld     ok
hello_World      Hello          HelloWorld     FAIL hello          helloWorld     FAIL
value_2          Value2         Value2         ok   value          value2         FAIL
sound_3d_mix     Sound3dMix     Sound3dMix     ok   sound          sound3dMix     FAIL
text_UTF8_load   Text           TextUTF8Load   FAIL text           textUTF8Load   FAIL
hello_           Hello          Hello          ok   hello          hello          ok
a__b             A              AB             FAIL a              aB             FAIL

FAILURES: 8 of 14

Guard page check, text "hello_" with its '\0' as the last readable byte:
  TextToPascal  CRASHED, read past the terminator
  TextToCamel   CRASHED, read past the terminator

RESULT: failures present

After:

input            TextToPascal   expected            TextToCamel    expected       
-------------------------------------------------------------------------------------
hello_world      HelloWorld     HelloWorld     ok   helloWorld     helloWorld     ok
hello_World      HelloWorld     HelloWorld     ok   helloWorld     helloWorld     ok
value_2          Value2         Value2         ok   value2         value2         ok
sound_3d_mix     Sound3dMix     Sound3dMix     ok   sound3dMix     sound3dMix     ok
text_UTF8_load   TextUTF8Load   TextUTF8Load   ok   textUTF8Load   textUTF8Load   ok
hello_           Hello          Hello          ok   hello          hello          ok
a__b             AB             AB             ok   aB             aB             ok

FAILURES: 0 of 14

Guard page check, text "hello_" with its '\0' as the last readable byte:
  TextToPascal  returned "Hello", no read past the terminator
  TextToCamel   returned "hello", no read past the terminator

RESULT: all checks passed

The last check writes "hello_" so its \0 is the final byte of a readable page with an unreadable page right behind it, which is why the read past the terminator shows up as a crash rather than as a wrong string.

TextToPascal("raylib_fun_videogames_programming") and TextToCamel("raylib_fun_videogames_programming") from examples/text/text_strings_management.c are unchanged, and TextToSnake() is not touched. The library and 225 examples build clean, and so do tools/rlparser and tools/rexm.

[raysan5]

@MaxFreedomPollard thanks for the review