Restructure theory chapers

[jfy133]

1. Background (part 1 of current aDNA)
2. NGS Sequencing
3. Ancient DNA (part 2 of current aDNA)
4. metagenomcs
5. environmental DNA
6. microbial genomics

As this makes aDNA shorter, and better follows the flow of a porject/summer school

[jfy133]

@warinner and I say start in April, and completion before summer school