Fix for non-mime messages

This fixes a critical issue with 0.4.3 (#40) where non-mime messages aren't handled properly.

Fix inline content handling (BROKEN)

This release is broken (#40) please update to 0.4.3.

• Allow underscore in mime-encoded header part #36
• Better inline content handling #29 #34
  • Part filtering using the new PartFilter
  • More dynamic mime parts (fewer references to parts)
  • Added removeAllHtmlParts, removeAllTextParts, getTextPartCount, getHtmlPartCount
  • getTextPart, getHtmlPart, getTextStream, getHtmlStream, getTextContent and getHtmlContent all now optionally take an integer index to get inline content parts other than the first one
  • getAllParts, getPartCount, getPart, getChild, getChildParts, getChildCount all optionally take a PartFilter to filter out returned parts
• Added more test code
• Code cleanup
• Fixed documentation

Apple mail parsing fixes

• Coding-style/scrutinizer fixes
• Fix for subject headers (do not have comments, quoted parts... verified from testing with various mail clients)
• Fix for removing content parts from messages with multiple content parts of a single type (discovered in apple mail messages) #29

Better email writing

• Moves writing functionality out of Message and MimePart and into writer classes
• Sets up a tree of parts for mime parts, allowing the structure of the original message to be better maintained
• Improves the writing functionality (more consistent with linebreaks, etc... cleaner code)
• Fix for alternative part with mixed part below it #29

Bug fixes/bad code cleanup

• Fix bad uses of empty #26
• better check for when to close the resource #27 (@styks1987)

Bug fixes

• Fix case-sensitive checks for Content-Type #21
• Fix removing/adding content parts #22
• Fix for some non-textual content streams #23
• Fix for signing messages without content parts #24 and #25

Fix message signing for multipart messages

• Fixes spacing between mime parts
• Fixes getSignableBody (based on what's considered valid by Enigmail) for multipart messages
• More strictly enforces CRLF instead of CR or LF when writing messages

Support for modifying read emails and creating multipart/signed messages

Included in this release:

• Fixes for UUEncoding and Base64Encoding for larger files
• Save feature for messages (can both read and write out)
• Basic edit features -- setRawHeader and setContent for MimeParts (and messages)
• Direct parsing from strings (not just streams) and convenience method Message::from($stringOrHandle)
• Add/remove attachments, content parts
• Read multipart/signed messages (no verification)
• Create multipart/signed messages with Message::setAsMultipartSigned, Message::getSignableBody and Message::getSignaturePart

Added additional charset and body content convenience methods

• Added support for WE8MSWIN1252
• Added Message::getTextContent and Message:getHtmlContent

Better charset support

This release introduces charset aliases for charsets not supported by mb_convert_encoding. It also falls back to iconv if a charset isn't supported by mb_convert_encoding at all allowing a much greater list of supported charsets.