apl_file: Use int32_t for chunk metadata
apl_date: Rename apl_read/writedatechunk, prefix with f

apl_fread/writedatechunk
apl_entry: Rename apl_save/loadentry functions

apl_fwriteentrychunk
apl_freadentrychunk
apl_user: Remove middle name field
apl_user: Add name API
apl_user: Add apl_newuser and apl_destroyuser functions
apl_user: Add apl_save/loaduser functions

Save encrypted user profile, much like how gradebooks are saved
Add user sanity test
.gitignore: Ignore apl_user files