Ver 2.1.0

• Modify description to mention that the library can also write SIE files, not just read them.
• Dev enhancement: Add configuration cache and parallell execution.
• accepts both CP437 and ISO-8859-1 on read by sampling the file and choosing the better decode
• explicitly rejects real non-ASCII UTF-8 SIE 1-4 input with a clear SieParseException. SIE 5 (XML) still accepts UTF-8 as per spec.
• keeps writing strict PC8 unchanged
• Dependency updates:
  • org.bouncycastle:bcpkix-jdk18on [1.83 -> 1.84]
  • org.glassfish.jaxb:jaxb-runtime [4.0.6 -> 4.0.7]
  • se.alipsa.nexus-release-plugin:se.alipsa.nexus-release-plugin.gradle.plugin [2.1.1 -> 2.1.2]