Improve colour highlights

- Sol: Used a less distracting color to show a modified file/buffer
- Sol: Similar change as above, to tabline as well
- Sol: Warning colour imporved (Previously was some bad shade of magenta)
- Sol: All the Above mentioned changes replicated for CTERM values as well
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- Luna: `Inactive Modified` colour is improved (Was a shade of red
                                                that was hard to read)
Merge pull request #466 from Pychimp/master

Improvements to Sol and Luna themes