Simplify incremental API by removing Partial

Some can play the role of the Partial constructor as well, making the
latter redundant. By removing it we simplify the API and the
implementation.
Rename Some to Many to reflect its new behavior

Some suggests that there's at least one record returned, which is no
longer the case.
Update examples to follow changes to incremental API
Export HasHeader from Incremental and Streaming
Follow API changes in examples
Add .cabal file for examples
Update .gitignore
Bump array upper bound
Improve performance of record parsing

Using a specialized implementation of sepBy1' improves the performance
on most benchmarks:

Name                                                      Mean
positional/decode/presidents/without conversion            94.07%
positional/decode/presidents/with conversion               87.83%
positional/decode/streaming/presidents/without conversion 106.90%
positional/decode/streaming/presidents/with conversion     89.04%
positional/encode/presidents/with conversion               96.83%
named/decode/presidents/without conversion                 84.36%
named/decode/presidents/with conversion                    92.15%
named/encode/presidents/with conversion                    95.87%
comparison/lazy-csv                                       103.79%
Use sepByDelim1' in the header parser as well

Shouldn't affect performance, as there's only one header per file.
Add a FromField instance for Either

On conversion failer the original field is returned wrapped in Left.
Another option would have been to return a data type that container
both the field and the error message. Fixes #45.
Add a travis-ci config
Export unsafeIndex

Fixes #43.
More examples of custom type conversion

Added examples for dealing with bad data and with multiple formats in
a single field.
Update travis-ci config

Since cabal check complains when we use -O2, we cannot use it.
Make benchmarks compile with older bytestring
Improve performance by using specialized parser combinator

The new combinator is specialized to detecting things seperated by
newlines.

The results are modest, but positive:

Name	Mean
positional/decode/presidents/without conversion            96.55%
positional/decode/presidents/with conversion               94.36%
positional/decode/streaming/presidents/without conversion  99.30%
positional/decode/streaming/presidents/with conversion     91.39%
positional/encode/presidents/with conversion               96.40%
named/decode/presidents/without conversion                100.25%
named/decode/presidents/with conversion                    94.10%
named/encode/presidents/with conversion                    96.18%
comparison/lazy-csv                                        93.81%
Move liftM2' to D.C.Util
Document HasHeader constructors
Fix bug where custom delimiters weren't escaped

Fixes #47.