add simple evolog examples

examples/greet-me.evl

@@ -0,0 +1,7 @@
+prompt_text("Hello user, what's your name? ").
+write_prompt_res(R) : @streamWrite[STDOUT, PROMPT] = R :- prompt_text(PROMPT), &stdout(STDOUT).
+usr_input_res(INP) : @streamReadLine[STDIN] = INP :- write_prompt_res(success(_)), &stdin(STDIN).
+write_greeting_res(R) : @streamWrite[STDOUT, GREETING] = R :- 
+	usr_input_res(success(line(NAME))), 
+	&stdlib_string_concat["Hello, it is the utmost pleasure to finally greet you from an Evolog program, ", NAME](GREETING),
+	&stdout(STDOUT).

examples/write_something.evl

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+outfile("/home/michael/asp_snippets/evolog-actions/hello.out").
+
+open_result(PATH, RES) : @fileOutputStream[PATH] = RES :- outfile(PATH).
+
+write_result(PATH, RES) : @streamWrite[STREAM, "HelloEvologWorld!"] = RES :- open_result(PATH, success(stream(STREAM))), outfile(PATH).
+
+can_close(PATH, FD) :- write_result(PATH, success(ok)), open_result(PATH, success(stream(FD))), outfile(PATH).
+
+close_result(PATH, RES) : @outputStreamClose[STREAM] = RES :- write_result(PATH, success(ok)), open_result(PATH, success(stream(STREAM))), outfile(PATH).