Update documentation

[sjaeckel]

Follow-up of #54

Anything else missing?

Someone volunteering?
If yes, please leave a comment and I'll add you to the list-item

• adler32, crc32 @sjaeckel
• base64 URL, strict
• blake2 hash
• blake2 mac
• chacha stream
• poly1305 mac
• chacha20poly1305 authenc
• dsa_set_pqg(), dsa_set_pqg_dsaparam(), dsa_generate_pqg(), dsa_set_key(), dsa_generate_key()
• der_sequence_shrink() @sjaeckel
• der_X_generalizedtime() @sjaeckel
• review DH + dh_set_pg(), dh_set_pg_dhparam(), dh_set_key() @sjaeckel
• ecc_sign_hash_rfc7518(), ecc_verify_hash_rfc7518()
• mem_neq @sjaeckel
• ocb3
• prng changes @sjaeckel
• rand_bn_bits() rand_bn_upto() @sjaeckel
• rc2_setup_ex()
• rsa_get_size(), rsa_sign_saltlen_get_max_ex(), rsa_import_x509(), rsa_import_pkcs8(), rsa_set_key(), rsa_set_factors(), rsa_set_crt_params() @sjaeckel
• sha3 hash
• sha3 shake (which is a bit special)
• stream cipher API
• PKCS#1 v1.5 + LTC_PKCS_1_V1_5_NA1 @sjaeckel
• fix Feature/doc (only crypt.tex + changes) #54 (review)
• add build instructions to README.md
• review "Configuring and Building the Library" @sjaeckel
• update libtomcrypt summary at http://www.libtom.net/LibTomCrypt/
• final check for any XXX-TODO in crypt.tex
• update CHANGES file
• delete TODO file (we have github for these)

[karel-m]

just added chacha20poly1305 doc

[karel-m]

added blake2 mac + poly1305 mac

[karel-m]

@sjaeckel now it's up to you. I do not plan more commits here.

I think we should merge this PR into release/1.18.0 and polish the rest there.