Refactor the whole code

[zimmski]

dbcb93d started to refactor the code even more. There is a lot to do but I do not have the open OSS ours right now. This needs to be done in small iterations. This issue keeps track on what is already done.

Purpose:

• Use the same code style everywhere, including naming things
• The port still suffers from unidiomatic Go code
• There are lot's of cases that can be made easier, e.g., early-returns

Unfinished functions:

• min
• max
• indexOf
• lastIndexOf
• runesIndexOf
• runesEqual
• runesIndex
• DiffMatchPatch.PatchAddContext
• DiffMatchPatch.PatchMake
• DiffMatchPatch.patchMake2
• DiffMatchPatch.PatchDeepCopy
• DiffMatchPatch.PatchApply
• DiffMatchPatch.PatchAddPadding
• DiffMatchPatch.PatchSplitMax
• DiffMatchPatch.PatchToText
• DiffMatchPatch.PatchFromText
• DiffMatchPatch.MatchMain
• DiffMatchPatch.MatchBitap
• DiffMatchPatch.matchBitapScore
• DiffMatchPatch.MatchAlphabet
• New
• splice
• DiffMatchPatch.DiffMain
• DiffMatchPatch.DiffMainRunes
• DiffMatchPatch.diffMainRunes
• DiffMatchPatch.diffCompute
• DiffMatchPatch.diffLineMode
• DiffMatchPatch.DiffBisect
• DiffMatchPatch.diffBisect
• DiffMatchPatch.diffBisectSplit
• DiffMatchPatch.DiffLinesToChars
• DiffMatchPatch.DiffLinesToRunes
• DiffMatchPatch.diffLinesToRunes
• DiffMatchPatch.diffLinesToRunesMunge
• DiffMatchPatch.DiffCharsToLines
• DiffMatchPatch.DiffCommonPrefix
• DiffMatchPatch.DiffCommonSuffix
• commonPrefixLength
• commonSuffixLength
• DiffMatchPatch.DiffCommonOverlap
• DiffMatchPatch.DiffHalfMatch
• DiffMatchPatch.diffHalfMatch
• DiffMatchPatch.diffHalfMatchI
• DiffMatchPatch.DiffCleanupSemantic
• diffCleanupSemanticScore
• DiffMatchPatch.DiffCleanupSemanticLossless
• DiffMatchPatch.DiffCleanupEfficiency
• DiffMatchPatch.DiffCleanupMerge
• DiffMatchPatch.DiffXIndex
• DiffMatchPatch.DiffPrettyHtml
• DiffMatchPatch.DiffPrettyText
• DiffMatchPatch.DiffText1
• DiffMatchPatch.DiffText2
• DiffMatchPatch.DiffLevenshtein
• DiffMatchPatch.DiffToDelta
• DiffMatchPatch.DiffFromDelta