docs: Fix a few typos

There are small typos in:
- example/ex-algo03.c
- m-algo.h
- m-core.h
- m-dict.h
- m-string.h

Fixes:
- Should read `occurrence` rather than `occurence`.
- Should read `fulfilled` rather than `fullfilled`.
- Should read `dictionaries` rather than `dictionnaries`.
- Should read `environment` rather than `environement`.
- Should read `unordered` rather than `undordered`.

m-core.h

@@ -34,7 +34,7 @@
 #include <stdlib.h>
 #include <assert.h>
 
-/* By default, always use stdio. Can be turned off in specific environement if needed
+/* By default, always use stdio. Can be turned off in specific environment if needed
    by defining M_USE_STDIO to 0 */
 #ifndef M_USE_STDIO
 # define M_USE_STDIO 1
@@ -43,7 +43,7 @@
 # include <stdio.h>
 #endif
 
-/* By default, always use stdarg. Can be turned off in specific environement if needed
+/* By default, always use stdarg. Can be turned off in specific environment if needed
    by defining M_USE_STDARG to 0 */
 #ifndef M_USE_STDARG
 # define M_USE_STDARG 1