support muxed accounts by default

• Muxed accounts are now supported by default (see #39)
• fix sep-0012 headers
• improve documentation

bugfixes

• fix sep-10 transaction post - clone request header - see #38
• fix revoke sponsorship operation (revokePreAuthTxSigner, revokeSha256HashSigner)
• improve documentation

sep-10 fix signed transaction post

• fixed transaction post for sep-10. see #37

sep-10 fix timbounds validation

• fixes time bounds validation - see #36

fix xdr parsing

• fix xdr parsing for claim predicate not
• add missing operations for xdr parsing

Protocol 18 fixes & improvements

• Fix for Unknown Enum Value in XdrClaimAtomType
• Improve AMM Test Cases

muxed accounts & memo support in SEP-10

adds muxed accounts and memo support in SEP 10 implementation - see #29
adds grace period to timebounds validation in SEP-10 implementation - see #30

Protocol 18 support (AMM)

1.2.2

prepare for release 1.2.2

null-safety version

add null-safety support

Update http package version

• update http package version
• update eventsource package version