word_copy: prevent tapping from erasing on non-sentence tutors

[Kevin DeLand]

This causes extraneous data in the log files. See this line.

[JackMostow]

This issue is too cryptic for me to understand the desired functionality or the problem with the code.

[Amogh Gupta]

This line is to log when the kid erases a letter in the writing activities.
Evelyn and I discussed that it might be useful to log when the letters are being erased.

1. Is this affecting other activities with writing boxes?
2. Is this logging at incorrect instances?

[JackMostow]

Thanks for explaining. @kevindeland - "extraneous" in what sense? Making it hard to tell what was written? Making log files too big?