Delete unused function

[bertfrees]

In the Fuzz Introspector report we can see that certain functions have 0% coverage by fuzzers. For one of these functions this is simply because it is never used:

• _lou_findOpcodeNumber

[bertfrees]

Also note that some functions are in the public API but could be deleted:

• lou_readCharFromFile

Some are only used in lou_hyphenate, which we eventually want to delete

• isHyphen

Some are underused for now because display and translation has not been completely separated yet:

• _lou_compileDisplayRule
• _lou_compileTranslationRule
• _lou_getDisplayTable
• _lou_getTranslationTable